He also appeared (voice only) in the Season 6 episode “The Extract Obliteration,” playing Words with Friends with Sheldon.
The world has lost one of its great minds, and The Big Bang Theory has lost one of its most reliably funny guest stars.
“It was truly such an honor getting to work with the incredible Stephen Hawking,” wrote Kaley Cuoco.
Hawking made his first appearance in the Season 5 episode “The Hawking Excitation,” when he visited Caltech and hired Howard (Simon Helberg) to perform maintenance on his wheelchair.