This is Phil Hartman's second episode, and he's already on his fourth character. We remember him mainly for Lionel Hutz and some actor guy we've not encountered yet, but it's easy to forget he was also the voice accompanying the heavenly escalator in "Bart Gets Hit By A Car", Moses (remember him?) and now, this guy.

He's a constant presence through this episode, but didn't catch on the way Hutz or to-be-revealed-actor did because he's quite sinister, and less fun. He won't appear again.
There's something comforting about Hartman's presence in any episode, even when his main characters aren't front and centre. I wouldn't even say I especially know him as the comic legend he was - it won't surprise anyone to learn that the Simpsons is my main reference point for him - but his performances are undeniably good. He's the sort of voice actor that doesn't have a wide range of unique or distinctive voices, but his performance's really set his characters apart. He only appears in 52 Simpsons episodes* but there are few guest stars who had as much of an impact on the show as him.
*I haven't double checked this number, don't yell at me if it's wrong.
This post is part of my "Every Simpsons Character Ever" series. For a list of my rules in this project, click here.