What is the greatest cameo performance?

Bill Murray in Zombieland

Donald Sutherland - JFK

That's not a cameo

Bob Hope in Spies Like Us

Charlton Heston - 'Gas Station Attendant', Wayne's World.

Also Spike Milligan - The Life of Brian (can't find a gif of that)

Donald Sutherland in JFK

Tom Cruise - Austin Powers: Goldmember

Leonard Rossiter in 2001: Space Odyssey

"What Kind Of American Are You?": Jesse Plemons' Civil War Scene

Tom Cruise/Tropical Thunder

I died laughing

Sharknado/Lavalantula crossover

TC - Austin Powers

I was thinking of Chris Evans' shot in Free Guy, but this wasn't bad either

the correct answer is always a famous actor appearing for exactly 40 seconds

Beatrice Straight in Network. It has earned her even an Oscar

Best sales movie ever made. COFFEE IS FOR WINNERS