Mr. X

The secret identity of Homer Simpson in The Simpsons episode titled "The Computer Wore Menace Shoes" (CABF02) where he gathers rumors and posts them to the internet as news. He is depicted in the media as a picture of himself with a black bag over his head with a question mark.

When Homer wins a pulitzer prize for uncovering dirt on people all over the city, he reveals his identity as Mr. X in order to collect the award and money. This turns out to put a stop to his rumor-gathering, becuase people stop sharing information whenever he's around. Without information to keep his website active, Homer eventually decides to make up his own conspiracy theories, including one which involves using flu shots for mind control.

Homer is abducted by an unknown organization and taken to an island occupied by people who "know too much". They tell him that he uncovered their conspiracy to use flu shots to make people buy stuff (that's why they are given out right before the holiday season). Everything on the island is designed to keep him drugged so he doesn't talk, including beverages, ice cream, and even croquet balls.

Mr. X is also a song by Ultravox off of their 1980 album Vienna. But, now that it's a cool Simpsons reference, that will no longer matter. It's not even like Ultravox are still together or anything like that:

I found the perfect picture, of a perfect stranger
It looked as if it were taken in the forties sometime
Judging by the style

He could be a killer, or a blind man with a cane
Perhaps he died in a car crash years ago
Right now, it's impossible to tell

I almost thought I saw him, standing, whistling on a bridge
I asked him the time but when he turned around
I saw it wasn't him at all

I'm still searching
I'm still searching

I saw him in an airport while he was sitting on a wing
I waved to him, but I don't think he noticed me
I've got a funny feeling I know who he is

Mr. X

Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X
Mr. X

(BTW, the whole island thing is a reference to The Prisoner. You'll want to check it out.)