Comment: If immortality means that people remember your name, then the "mad Roman emperor" Caligula is definitely immortal. Everybody's heard of him even if they've never cracked a history book, which just goes to show that being a "good ruler" doesn't necessarily guarantee that your name will go down in posterity. Moral, competent leaders come and go, fading into obscurity, but juicy villains like Caligula live on forever in movies and plays and novels and TV productions. The only problem is that most of what we think we know about him probably isn't true.
Caligula, of course, is the most notorious Roman emperor, with a reputation for insanity, cruelty and sexual depravity based almost completely on his depiction in the media and in absurd sensationalized films like Bob Guccione's Caligula, one of the vilest and most degenerate, pornographic and unhistorical movies I've ever seen. This image of Caligula as an insane emperor is so engrained in popular culture that most people would automatically reject the idea that it's probably not accurate.