diff --git a/core/lib/Drupal/Component/Plugin/CategorizingPluginManagerInterface.php b/core/lib/Drupal/Component/Plugin/CategorizingPluginManagerInterface.php
new file mode 100644
index 0000000..bb9df77
--- /dev/null
+++ b/core/lib/Drupal/Component/Plugin/CategorizingPluginManagerInterface.php
@@ -0,0 +1,50 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Component\Plugin\CategorizingPluginManagerInterface.
+ */
+
+namespace Drupal\Component\Plugin;
+
+/**
+ * Defines an interface for plugin managers that categorize plugin definitions.
+ */
+interface CategorizingPluginManagerInterface extends PluginManagerInterface {
+
+  /**
+   * Gets the names of all categories.
+   *
+   * @return string[]
+   *   An array of translated categories, sorted alphabetically.
+   */
+  public function getCategories();
+
+  /**
+   * Gets sorted definitions.
+   *
+   * @param array[]|null $definitions
+   *   (optional) The definitions to sort. If omitted, all definitions are used.
+   *
+   * @return array[]
+   *   An array of plugin definitions, sorted by category and label.
+   */
+  public function getSortedDefinitions(array $definitions = NULL);
+
+  /**
+   * Gets sorted definitions grouped by category.
+   *
+   * In addition to grouping, both categories and its entries are sorted,
+   * whereas definitions are sorted by label.
+   *
+   * @param array[]|null $definitions
+   *   (optional) The definitions to group. If omitted, all definitions are
+   *   used.
+   *
+   * @return array[]
+   *   Keys are category names, and values are arrays of which the keys are
+   *   plugin IDs and the values are plugin definitions.
+   */
+  public function getGroupedDefinitions(array $definitions = NULL);
+
+}
diff --git a/core/lib/Drupal/Core/Action/ActionManager.php b/core/lib/Drupal/Core/Action/ActionManager.php
index 1baf427..b4e5246 100644
--- a/core/lib/Drupal/Core/Action/ActionManager.php
+++ b/core/lib/Drupal/Core/Action/ActionManager.php
@@ -7,8 +7,10 @@
 
 namespace Drupal\Core\Action;
 
+use Drupal\Component\Plugin\CategorizingPluginManagerInterface;
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\CategorizingPluginManagerTrait;
 use Drupal\Core\Plugin\DefaultPluginManager;
 
 /**
@@ -19,7 +21,9 @@
  * @see \Drupal\Core\Action\ActionBase
  * @see plugin_api
  */
-class ActionManager extends DefaultPluginManager {
+class ActionManager extends DefaultPluginManager implements CategorizingPluginManagerInterface {
+
+  use CategorizingPluginManagerTrait;
 
   /**
    * Constructs a new class instance.
diff --git a/core/lib/Drupal/Core/Annotation/Action.php b/core/lib/Drupal/Core/Annotation/Action.php
index 5d0937d..b35f70d 100644
--- a/core/lib/Drupal/Core/Annotation/Action.php
+++ b/core/lib/Drupal/Core/Annotation/Action.php
@@ -59,4 +59,13 @@ class Action extends Plugin {
    */
   public $type = '';
 
+  /**
+   * The category under which the action should be listed in the UI.
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
+   */
+  public $category;
+
 }
diff --git a/core/lib/Drupal/Core/Block/BlockManager.php b/core/lib/Drupal/Core/Block/BlockManager.php
index 75f9527..086016d 100644
--- a/core/lib/Drupal/Core/Block/BlockManager.php
+++ b/core/lib/Drupal/Core/Block/BlockManager.php
@@ -10,9 +10,9 @@
 use Drupal\Component\Plugin\FallbackPluginManagerInterface;
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\CategorizingPluginManagerTrait;
 use Drupal\Core\Plugin\Context\ContextAwarePluginManagerTrait;
 use Drupal\Core\Plugin\DefaultPluginManager;
-use Drupal\Core\StringTranslation\StringTranslationTrait;
 
 /**
  * Manages discovery and instantiation of block plugins.
@@ -23,17 +23,13 @@
  */
 class BlockManager extends DefaultPluginManager implements BlockManagerInterface, FallbackPluginManagerInterface {
 
-  use StringTranslationTrait;
+  use CategorizingPluginManagerTrait {
+    getSortedDefinitions as traitGetSortedDefinitions;
+    getGroupedDefinitions as traitGetGroupedDefinitions;
+  }
   use ContextAwarePluginManagerTrait;
 
   /**
-   * An array of all available modules and their data.
-   *
-   * @var array
-   */
-  protected $moduleData;
-
-  /**
    * Constructs a new \Drupal\Core\Block\BlockManager object.
    *
    * @param \Traversable $namespaces
@@ -56,61 +52,27 @@ public function __construct(\Traversable $namespaces, CacheBackendInterface $cac
    */
   public function processDefinition(&$definition, $plugin_id) {
     parent::processDefinition($definition, $plugin_id);
-
-    // Ensure that every block has a category.
-    if (empty($definition['category'])) {
-      $definition['category'] = $this->getModuleName($definition['provider']);
-    }
-  }
-
-  /**
-   * Gets the name of the module.
-   *
-   * @param string $module
-   *   The machine name of a module.
-   *
-   * @return string
-   *   The human-readable module name if it exists, otherwise the
-   *   machine-readable module name.
-   */
-  protected function getModuleName($module) {
-    // Gather module data.
-    if (!isset($this->moduleData)) {
-      $this->moduleData = system_get_info('module');
-    }
-    // If the module exists, return its human-readable name.
-    if (isset($this->moduleData[$module])) {
-      return $this->t($this->moduleData[$module]['name']);
-    }
-    // Otherwise, return the machine name.
-    return $module;
+    $this->processDefinitionCategory($definition);
   }
 
   /**
    * {@inheritdoc}
    */
-  public function getCategories() {
-    $categories = array_unique(array_values(array_map(function ($definition) {
-      return $definition['category'];
-    }, $this->getDefinitions())));
-    natcasesort($categories);
-    return $categories;
+  public function getSortedDefinitions(array $definitions = NULL) {
+    // Sort the plugins first by category, then by label.
+    $definitions = $this->traitGetSortedDefinitions($definitions, 'admin_label');
+    // Do not display the 'broken' plugin in the UI.
+    unset($definitions['broken']);
+    return $definitions;
   }
 
   /**
    * {@inheritdoc}
    */
-  public function getSortedDefinitions() {
-    // Sort the plugins first by category, then by label.
-    $definitions = $this->getDefinitionsForContexts();
-    uasort($definitions, function ($a, $b) {
-      if ($a['category'] != $b['category']) {
-        return strnatcasecmp($a['category'], $b['category']);
-      }
-      return strnatcasecmp($a['admin_label'], $b['admin_label']);
-    });
+  public function getGroupedDefinitions(array $definitions = NULL) {
+    $definitions = $this->traitGetGroupedDefinitions($definitions, 'admin_label');
     // Do not display the 'broken' plugin in the UI.
-    unset($definitions['broken']);
+    unset($definitions[$this->t('Block')]['broken']);
     return $definitions;
   }
 
diff --git a/core/lib/Drupal/Core/Block/BlockManagerInterface.php b/core/lib/Drupal/Core/Block/BlockManagerInterface.php
index 2fa8611..592a9a3 100644
--- a/core/lib/Drupal/Core/Block/BlockManagerInterface.php
+++ b/core/lib/Drupal/Core/Block/BlockManagerInterface.php
@@ -7,27 +7,12 @@
 
 namespace Drupal\Core\Block;
 
+use Drupal\Component\Plugin\CategorizingPluginManagerInterface;
 use Drupal\Core\Plugin\Context\ContextAwarePluginManagerInterface;
 
 /**
  * Provides an interface for the discovery and instantiation of block plugins.
  */
-interface BlockManagerInterface extends ContextAwarePluginManagerInterface {
-
-  /**
-   * Gets the names of all block categories.
-   *
-   * @return array
-   *   An array of translated categories, sorted alphabetically.
-   */
-  public function getCategories();
-
-  /**
-   * Gets the sorted definitions.
-   *
-   * @return array
-   *   An array of plugin definitions, sorted by category and admin label.
-   */
-  public function getSortedDefinitions();
+interface BlockManagerInterface extends ContextAwarePluginManagerInterface, CategorizingPluginManagerInterface {
 
 }
diff --git a/core/lib/Drupal/Core/Condition/Annotation/Condition.php b/core/lib/Drupal/Core/Condition/Annotation/Condition.php
index 55834d0..d796865 100644
--- a/core/lib/Drupal/Core/Condition/Annotation/Condition.php
+++ b/core/lib/Drupal/Core/Condition/Annotation/Condition.php
@@ -59,4 +59,13 @@ class Condition extends Plugin {
    */
   public $condition = array();
 
+  /**
+   * The category under which the condition should listed in the UI.
+   *
+   * @var \Drupal\Core\Annotation\Translation
+   *
+   * @ingroup plugin_translatable
+   */
+  public $category;
+
 }
diff --git a/core/lib/Drupal/Core/Condition/ConditionManager.php b/core/lib/Drupal/Core/Condition/ConditionManager.php
index c1e309a..809f28f 100644
--- a/core/lib/Drupal/Core/Condition/ConditionManager.php
+++ b/core/lib/Drupal/Core/Condition/ConditionManager.php
@@ -7,10 +7,12 @@
 
 namespace Drupal\Core\Condition;
 
+use Drupal\Component\Plugin\CategorizingPluginManagerInterface;
 use Drupal\Core\Cache\CacheBackendInterface;
 use Drupal\Core\Executable\ExecutableManagerInterface;
 use Drupal\Core\Executable\ExecutableInterface;
 use Drupal\Core\Extension\ModuleHandlerInterface;
+use Drupal\Core\Plugin\CategorizingPluginManagerTrait;
 use Drupal\Core\Plugin\Context\ContextAwarePluginManagerTrait;
 use Drupal\Core\Plugin\DefaultPluginManager;
 
@@ -23,8 +25,9 @@
  *
  * @ingroup plugin_api
  */
-class ConditionManager extends DefaultPluginManager implements ExecutableManagerInterface {
+class ConditionManager extends DefaultPluginManager implements ExecutableManagerInterface, CategorizingPluginManagerInterface {
 
+  use CategorizingPluginManagerTrait;
   use ContextAwarePluginManagerTrait;
 
   /**
diff --git a/core/lib/Drupal/Core/Plugin/CategorizingPluginManagerTrait.php b/core/lib/Drupal/Core/Plugin/CategorizingPluginManagerTrait.php
new file mode 100644
index 0000000..6cb8c5a
--- /dev/null
+++ b/core/lib/Drupal/Core/Plugin/CategorizingPluginManagerTrait.php
@@ -0,0 +1,114 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Core\Plugin\CategorizingPluginManagerTrait.
+ */
+
+namespace Drupal\Core\Plugin;
+
+use Drupal\Core\StringTranslation\StringTranslationTrait;
+
+/**
+ * Provides a trait for the CategorizingPluginManagerInterface.
+ *
+ * The trait provides methods for categorizing plugin definitions based on a
+ * 'category' key. The plugin manager should make sure there is a default
+ * category. For that the trait's processDefinitionCategory() method can be
+ * invoked from the processDefinition() method.
+ *
+ * @see \Drupal\Component\Plugin\CategorizingPluginManagerInterface
+ */
+trait CategorizingPluginManagerTrait {
+
+  use StringTranslationTrait;
+
+  /**
+   * An array of all available modules and their data.
+   *
+   * @var array
+   */
+  protected $moduleData;
+
+  /**
+   * Processes a definition to ensure there is a category.
+   *
+   * If the definition lacks a category, it defaults to the providing module.
+   *
+   * @param array $definition
+   *   The plugin definition.
+   */
+  protected function processDefinitionCategory(&$definition) {
+    // Ensure that every plugin has a category.
+    if (empty($definition['category'])) {
+      // Default to the human readable module name if the provider is a module;
+      // otherwise the provider machine name is used.
+      $definition['category'] = $this->getModuleName($definition['provider']);
+    }
+  }
+
+  /**
+   * Gets the name of the module.
+   *
+   * @param string $module
+   *   The machine name of a module.
+   *
+   * @return string
+   *   The human-readable module name if it exists, otherwise the
+   *   machine-readable module name.
+   */
+  protected function getModuleName($module) {
+    // Gather module data.
+    if (!isset($this->moduleData)) {
+      $this->moduleData = system_get_info('module');
+    }
+    // If the module exists, return its human-readable name.
+    if (isset($this->moduleData[$module])) {
+      return $this->t($this->moduleData[$module]['name']);
+    }
+    // Otherwise, return the machine name.
+    return $module;
+  }
+
+  /**
+   * Implements \Drupal\Component\Plugin\CategorizingPluginManagerInterface::getCategories().
+   */
+  public function getCategories() {
+    /** @var \Drupal\Core\Plugin\CategorizingPluginManagerTrait|\Drupal\Component\Plugin\PluginManagerInterface $this */
+    $categories = array_unique(array_values(array_map(function ($definition) {
+      return $definition['category'];
+    }, $this->getDefinitions())));
+    natcasesort($categories);
+    return $categories;
+  }
+
+  /**
+   * Implements \Drupal\Component\Plugin\CategorizingPluginManagerInterface::getSortedDefinitions().
+   */
+  public function getSortedDefinitions(array $definitions = NULL, $label_key = 'label') {
+    // Sort the plugins first by category, then by label.
+    /** @var \Drupal\Core\Plugin\CategorizingPluginManagerTrait|\Drupal\Component\Plugin\PluginManagerInterface $this */
+    $definitions = isset($definitions) ? $definitions : $this->getDefinitions();
+    uasort($definitions, function ($a, $b) use ($label_key) {
+      if ($a['category'] != $b['category']) {
+        return strnatcasecmp($a['category'], $b['category']);
+      }
+      return strnatcasecmp($a[$label_key], $b[$label_key]);
+    });
+    return $definitions;
+  }
+
+  /**
+   * Implements \Drupal\Component\Plugin\CategorizingPluginManagerInterface::getGroupedDefinitions().
+   */
+  public function getGroupedDefinitions(array $definitions = NULL, $label_key = 'label') {
+    /** @var \Drupal\Core\Plugin\CategorizingPluginManagerTrait|\Drupal\Component\Plugin\PluginManagerInterface $this */
+    $definitions = $this->getSortedDefinitions(isset($definitions) ? $definitions : $this->getDefinitions(), $label_key);
+    $grouped_definitions = array();
+    foreach ($definitions as $id => $definition) {
+      $grouped_definitions[(string) $definition['category']][$id] = $definition;
+    }
+    return $grouped_definitions;
+  }
+
+}
diff --git a/core/modules/block/src/BlockListBuilder.php b/core/modules/block/src/BlockListBuilder.php
index 1d11f99..07cbcc6 100644
--- a/core/modules/block/src/BlockListBuilder.php
+++ b/core/modules/block/src/BlockListBuilder.php
@@ -334,9 +334,10 @@ public function buildForm(array $form, FormStateInterface $form_state) {
     $form['place_blocks']['list']['#type'] = 'container';
     $form['place_blocks']['list']['#attributes']['class'][] = 'entity-meta';
 
-    // Sort the plugins first by category, then by label.
-    $plugins = $this->blockManager->getSortedDefinitions();
-    foreach ($plugins as $plugin_id => $plugin_definition) {
+    // Only add blocks which work without any available context.
+    $definitions = $this->blockManager->getDefinitionsForContexts();
+    $sorted_definitions = $this->blockManager->getSortedDefinitions($definitions);
+    foreach ($sorted_definitions as $plugin_id => $plugin_definition) {
       $category = String::checkPlain($plugin_definition['category']);
       $category_key = 'category-' . $category;
       if (!isset($form['place_blocks']['list'][$category_key])) {
diff --git a/core/tests/Drupal/Tests/Core/Plugin/CategorizingPluginManagerTraitTest.php b/core/tests/Drupal/Tests/Core/Plugin/CategorizingPluginManagerTraitTest.php
new file mode 100644
index 0000000..7c151c0
--- /dev/null
+++ b/core/tests/Drupal/Tests/Core/Plugin/CategorizingPluginManagerTraitTest.php
@@ -0,0 +1,151 @@
+<?php
+
+/**
+ * @file
+ * Contains \Drupal\Tests\Core\Plugin\CategorizingPluginManagerTraitTest.
+ */
+
+namespace Drupal\Tests\Core\Plugin {
+
+  use Drupal\Component\Plugin\CategorizingPluginManagerInterface;
+  use Drupal\Core\Plugin\CategorizingPluginManagerTrait;
+  use Drupal\Core\Plugin\DefaultPluginManager;
+  use Drupal\Tests\UnitTestCase;
+
+  /**
+   * @coversDefaultClass \Drupal\Core\Plugin\CategorizingPluginManagerTrait
+   * @group Plugin
+   */
+  class CategorizingPluginManagerTraitTest extends UnitTestCase {
+
+    /**
+     * The plugin manager to test.
+     *
+     * @var \Drupal\Component\Plugin\CategorizingPluginManagerInterface|\PHPUnit_Framework_MockObject_MockObject
+     */
+    protected $pluginManager;
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function setUp() {
+      $this->pluginManager = new CategorizingPluginManagerImpl();
+      $this->pluginManager->setStringTranslation($this->getStringTranslationStub());
+    }
+
+    /**
+     * @covers ::getCategories
+     */
+    public function testGetCategories() {
+      $this->assertSame(array_values($this->pluginManager->getCategories()), [
+          'fruits',
+          'vegetables',
+        ]);
+    }
+
+    /**
+     * @covers ::getSortedDefinitions
+     */
+    public function testGetSortedDefinitions() {
+      $sorted = $this->pluginManager->getSortedDefinitions();
+      $this->assertSame(array_keys($sorted), ['apple', 'mango', 'cucumber']);
+    }
+
+    /**
+     * @covers ::getGroupedDefinitions
+     */
+    public function testGetGroupedDefinitions() {
+      $grouped = $this->pluginManager->getGroupedDefinitions();
+      $this->assertSame(array_keys($grouped), ['fruits', 'vegetables']);
+      $this->assertSame(array_keys($grouped['fruits']), ['apple', 'mango']);
+      $this->assertSame(array_keys($grouped['vegetables']), ['cucumber']);
+    }
+
+    /**
+     * @covers ::processDefinitionCategory
+     */
+    public function testProcessDefinitionCategory() {
+      // Existing category.
+      $definition = [
+        'label' => 'some',
+        'provider' => 'core',
+        'category' => 'bag',
+      ];
+      $this->pluginManager->processDefinition($definition, 'some');
+      $this->assertSame($definition['category'], 'bag');
+
+      // No category, provider without label.
+      $definition = [
+        'label' => 'some',
+        'provider' => 'core',
+      ];
+      $this->pluginManager->processDefinition($definition, 'some');
+      $this->assertSame($definition['category'], 'core');
+
+      // No category, provider is module with label.
+      $definition = [
+        'label' => 'some',
+        'provider' => 'node',
+      ];
+      $this->pluginManager->processDefinition($definition, 'some');
+      $this->assertSame($definition['category'], 'Node');
+    }
+  }
+
+  /**
+   * Class that allows testing the trait.
+   */
+  class CategorizingPluginManagerImpl extends DefaultPluginManager implements CategorizingPluginManagerInterface {
+
+    use CategorizingPluginManagerTrait;
+
+    /**
+     * Replace the constructor so we can instantiate a stub.
+     */
+    public function __construct() {
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * Provides some test definitions to the trait.
+     */
+    public function getDefinitions() {
+      return [
+        'cucumber' => [
+          'label' => 'cucumber',
+          'category' => 'vegetables',
+        ],
+        'apple' => [
+          'label' => 'apple',
+          'category' => 'fruits',
+        ],
+        'mango' => [
+          'label' => 'mango',
+          'category' => 'fruits',
+        ],
+      ];
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function processDefinition(&$definition, $plugin_id) {
+      parent::processDefinition($definition, $plugin_id);
+      $this->processDefinitionCategory($definition);
+    }
+  }
+}
+
+namespace {
+
+  /**
+   * "Mocks" system_get_info() as needed for the test.
+   */
+  if (!function_exists('system_get_info')) {
+
+    function system_get_info($type, $name = NULL) {
+      return ['node' => ['name' => 'Node']];
+    }
+  }
+}