NPC – Groundskeeper Wyllithen and Mayor Quimby
The Simpsons is the longest running cartoon (or TV series for that matter) in US history. The comic was originally created by Matt Groening. There are only 2 references that I could find:
Groundskeeper Wyllithen in Silvermoon even looks like his namesake, Groundskeeper Willie, the Irish red haired gardener in the Simpsons. Complete with shovel.
In the DeathKnight starting area, you can find the other Simpsons NPC. You can’t see it unless you’re doing the early DK quests.
Mayor Quimby‘s name is exactly the same as in the Simpsons, and he even has the same portly figure.