Board Thread:Origin Usernames Corkboard/@comment-37496631-20181114123436/@comment-28980314-20181217222714

You have to go through the Flaw and Order questline to get Sideshow Bob, however, part 2 of Flaw and Order might appear when you at a random level (though the minimum level is 5) so you could be on level 400 or something and it suddenly appears.