Front (category)

attachment_link	Allows you to change an attachment link (a file from the media library).
body_class	Allows you to change the list of CSS classes assigned to the `<body>` tag.
do_parse_request	Allows you to completely disable processing of the current request.
do_robotstxt	Allows you to completely replace the content of the `/robots.txt` page.
get_canonical_url	Allows you to change the canonical URL that WordPress outputs for posts.
login_enqueue_scripts	Allows you to enqueue scripts and styles on the wp-login.php page.
mod_rewrite_rules	Allows you to change, add, or remove any rules in the `.htaccess` file.
robots_txt	Allows you to append content to the already generated `/robots.txt` page.
script_loader_tag	Allows you to change the HTML of a `<script>` tag enqueued for output by `wp_enqueue_script()`.
shortcode_atts_(shortcode)	Filters the default attributes of the specified shortcode.
the_content	Filters post content after it is retrieved from the database but before it is displayed.
wp_headers	Allows you to change HTTP headers before they are sent to the browser.
wp_lazy_loading_enabled	Allows you to enable or disable the `loading` attribute for the specified tag in the specified context.

Theme (template)

after_switch_theme	Fires after the theme has been switched to a new one, when the theme is activated.
document_title_parts	Allows you to change the title of a WordPress site page.
get_search_form	Allows you to change the HTML of the search form.
site_icon_meta_tags	Allows you to change or extend the list of HTML meta tags for the site icon.
switch_theme	Fires when the theme is switched. Used when deactivating a theme.
template_include	Allows changing the path to the selected template file used to display the current page, such as `single.php` or `page.php`.
template_redirect	Fires before WordPress determines which template file to use to display the content.
theme_(post_type)_templates	Allows you to add or remove page templates for post types. These templates can be selected when publishing a post in the admin area.
theme_templates	Allows adding/removing page (post) template files used in the template selector when editing a post.
wp_after_load_template	Fires after a template is included (output).
wp_before_load_template	Fires before a template is included (output).
wp_enqueue_scripts	Allows you to enqueue scripts and styles for loading on the front end.
wp_footer	Fires in the page footer. Scripts, styles, and other assets are commonly included when this event fires. This is one of the main theme hooks.
wp_head	Fires in the page's `<head>` section. Scripts such as jQuery, site CSS, and SEO metadata such as title, description, and robots are commonly output at this point. This is one of the primary WordPress theme hooks.

LogIn and Registrations

authenticate	Allows you to perform additional checks on a user's authentication credentials (login/password) before the user is authenticated.
login_footer	Fires after the form is output on the login/authorization page (wp-login.php).
login_head	Fires in the `<head>` section of the login/registration page (`wp-login.php`).
login_header	Fires immediately after the opening `<body>` tag on the login/authorization page (`wp-login.php`), before the form is output.
login_headerurl	Allows you to change the URL of the logo link above the registration/login form. By default, the link points to wordpress.org.
login_redirect	Allows you to change the URL to which a user is redirected after logging in.
login_url	Allows you to change the login page URL (link).
register_form	Fires after the “Email” field is displayed in the user registration form on the `wp-login.php` page.
registration_errors	Allows you to add custom registration checks and change error messages on the registration page.

Comments (pings)

comment_form_default_fields	Allows you to modify, add, or remove comment form fields such as `name`, `email`, and `website`.
comment_post	Fires immediately after a comment is added to the database. The event passes the comment ID, status, and data.
comments_popup_link_attributes	Filters the attributes of the link output by comments_popup_link().
edit_comment	Fires immediately after a comment has been updated in the database.
get_comment_author_link	Allows you to change the link to the commenter's website returned by get_comment_author_link().
preprocess_comment	Filters comment data before it is sanitized and added to the database. The filter fires at the very beginning of wp_new_comment(), which adds a new comment.
respond_link	Filters the response URL (the link to the comments) when a post has no comments. Clicking the link takes the user to the comment form (the link contains an anchor).
wp_count_comments	Allows you to change the comment count for a specified post or for the site as a whole.

Widgets

dynamic_sidebar_params	Allows you to change the parameters passed to a widget's display callback.
sidebars_widgets	Allows you to change the list of sidebars and the widgets assigned to them.
widget_title	Allows you to change a widget title on the front end.

Navigation Menu (nav_menu)

nav_menu_css_class	Allows changing the set of CSS classes assigned to a menu item.
nav_menu_item_args	Allows you to change the arguments of an individual navigation menu item in `wp_nav_menu()`.
nav_menu_item_id	Allows you to change the ID attribute of a menu item's `<li>` element.
nav_menu_item_title	Allows you to change a menu item's title (link anchor text).
nav_menu_link_attributes	Allows changing the `<a>` HTML attributes of a menu item: title, target, rel, and href.
nav_menu_meta_box_object	Allows you to change the object used to build a meta box in the menu item selection accordion on the admin menu creation page.
nav_menu_submenu_css_class	Allows you to change the CSS classes added to nested `ul` elements (menu lists). The `sub-menu` class is added by default.
pre_wp_nav_menu	Allows you to change the output of `wp_nav_menu()` at an early stage, before the function's main code runs.
walker_nav_menu_start_el	Allows you to change the output of a menu item's opening element.
wp_nav_menu	Allows you to change the navigation menu HTML before it is displayed.
wp_nav_menu_(menu_slug)_items	Allows you to change the generated HTML of each menu's items individually based on its `slug`.
wp_nav_menu_args	Allows you to change the arguments passed to `wp_nav_menu()` after they have been merged with the default values.
wp_nav_menu_container_allowedtags	Allows you to extend the list of HTML tags accepted in the `'container'` parameter when a menu is output by `wp_nav_menu()`. Filters the list of menu container tags.
wp_nav_menu_items	Allows you to change the generated HTML of menu items.
wp_nav_menu_objects	Allows you to modify the sorted list of menu item objects before the menu HTML is generated from them.