Arthur Jeffries was the host of the kids’ science show, “Professor Proton.” Sheldon and Leonard looked up to him as kids, and they later become involved with him in real life, much to their delight.
In season seven, Jeffries dies, but that doesn’t mean he was off the show. He kept coming up for a few more appearances in Sheldon’s dreams, usually looking a little disoriented and wearing a “Star Wars” costume.
Melissa Rauch as Bernadette Wolowitz – Then
Bernadette is a former waitress at The Cheesecake Factory who has finished her Ph.D. in microbiology. She was introduced to us in the third season when Penny introduced her to Howard.
At first, the two weren’t able to find anything in common but then bonded over the fact that they both have overbearing mothers. In season 4, Howard proposes to her, and they get married in season 6. Later, the two have two kids — a daughter named Halley and a son named Neil.
Melissa Rauch as Bernadette Wolowitz – Now
Before her major role in TBBT, Melissa made some other television appearances. She played minor parts in "The Office" and "True Blood."
Melissa also acted in a few movies such as "The Bronze" in 2015 and "Are You Here" in 2013. The actress (along with Mayim) got a raise after she signed on for season 11 and 12 and started making a whopping $500,000 per episode.
Bob Newhart as Arthur Jeffries — Now
Bib Newhart needs no introduction, but we're going to brave one anyway. With his brilliant example of deadpan comedy, Newhart has been a legend for many decades now. He had his big break in 1960 with "The Button-Down Mind Of Bob Newhart," his album of comedic monologues, and went on to have one of the most prolific careers the comedy world has ever seen.
After his role in "The Big Bang Theory," Newhart went on to reprise his role as Professor Proton (though mostly as a voice-over) in "Young Sheldon," the prequel show, depicting Sheldon's life as a little kid.
Brian Posehn as Bert Kibbler — Then
Bert is another researcher from Caltech — a geologist who enjoys the occasional rock pun, as his profession requires. In season 7, Bert expresses some interest in Amy, who remains oblivious until told about it by her friends.
We wouldn't worry about Bert's fate, though. He later turns out as a pretty sweet guy with a pretty cool job, and he even gets a fancy research grant most of the gang can only dream of.