This userscript no longer works because Stack Exchange has replaced bookmarks with "saves" in October 2022. Saves are private and so can't be queried via the Stack Exchange Data Explorer.
Userscript to fetch the list of users that bookmarked a question on any Stack Exchange website.
Simply click the person icon below the bookmark icon to open the list. Note that the icon is only visible when there is at least one bookmark. Bookmarking users are listed in the order in which they created their bookmarks, newest to oldest.
This script is MIT licensed.