WordPress File wp-includes/comment.php

comment_save_pre

Filters the comment content before it is updated in the database.

delete_comment

Fires immediately before a comment is deleted from the database.

deleted_comment

Fires immediately after a comment is deleted from the database.

do_all_pings

Fires immediately after the do_pings event to hook services individually.

duplicate_comment_id

Filters the ID, if any, of the duplicate comment found when creating a new comment.

edit_comment

Fires immediately after a comment is updated in the database.