This is a phrase used to introduce aliases, nicknames, working names, legalised names, author’s pen names and so on. Identical in meaning to the old English word Yclept, it is often abbreviated to AKA.
one of the things that slowly drove the r/batmanarkham subreddit to the brink of insanity (im actually not sure if this was the start of it but it was talked about that being the cause of the madness)