Wait, so we're allowed to base stuff on personal beliefs then?
I figured you meant tangible things that went extinct.
Oh well, either way...these no longer exist:
PB Max
Buger Chef (and Jeff, apparently)
Royals (mint M&Ms with crowns instead of Ms printed on them, only came in brown and green)
Bubble-Eez
Peanut Butter Boppers
Mountain Dew Pitch Black 2
ONTV
My dog.