With The Big Bang Theory running as long as it did, it's no surprise that it spawned its fair share of hilarious running gags ...

The Big Bang Theory introduced an underrated episode type that could be beautifully utilized more often in Georgie & Mandy’s First Marriage.

Johnny Galecki is probably the best-known Roseanne veteran to have appeared on The Big Bang Theory, but he's far from the only actor to pop up on both shows.