Erwin Schrodinger

Erwin Schrödinger turns up as one of the thousands of preserved heads populating New New York's future, a minor curiosity glimpsed among the collection of historical figures Futurama likes to resurrect for a punchline. True to form, he exists mostly to deliver one joke: nobody can quite say for certain whether he's alive or dead.

The gag writes itself into physics history and then gets out of the way, letting the joke land purely on the premise of a scientist perpetually trapped inside his own famous paradox. Maurice LaMarche gives the line just enough dry, professorial exasperation to sell the wordplay without overplaying it, which is exactly the register Futurama's best cameo jokes need.