The biggest connection is definitely "Big Bang Theory" creator Chuck Lorre.

Before becoming the hit-sitcom machine we know today, Lorre was a writer and producer for "Roseanne" from 1990 to 1992, the show's third and fourth seasons.

So he knew Johnny Galecki, Laurie Metcalf and Sara Gilbert before casting them on "The Big Bang Theory." He also brought along a few other folks he worked with on the "Roseanne" set.

Don Foster serves as a creative consultant on "Big Bang," as he did on "Roseanne" -- creative consultants work with executive producers (such as Lorre) on story ideas and fine-tuning scripts.

Foster has worked as either a consultant, writer or executive producer on the other Lorre hits "Mike & Molly," "Two and a Half Men" and "Dharma & Greg."

You may recognize the short-sleeve-over-long-sleeve T-shirt look sported by "The Big Bang Theory's" Sheldon as one also sported by D.J. Conner on "Roseanne" -- if so, you're recognizing the work of Mary T. Quigley, the costume designer on both shows (a role she also fills on "Two and a Half Men").

This phenomenon isn't just limited to "Roseanne" castaways, though. While former "Roseanne" star Laurie Metcalf has a recurring spot as Sheldon's mother on "Big Bang," Leonard's mother is played by Christine Baranski, who starred in another Lorre hit, "Cybill," from 1995 to 1998.

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