Several The Big Bang Theory. The two Chuck Lorre-produced series are among the most successful television shows of all time. Though not clearly set within the same universe, both shows did at times reference each other in small ways. An obvious connection between both is some familiar faces from Two and A Half Men also appearing on The Big Bang Theory.
Two and A Half Men aired for 12 seasons from 2003 to 2015, starring Charlie Sheen, Jon Cryer, and Angus T. Jones. The show revolved around Charlie Harper, whose rich playboy lifestyle is complicated after his divorced brother Alan and his nephew Jake move into his Malibu beach house. In season 9 of Two and A Half Men, Charlie Sheen was replaced by Ashton Kutcher playing billionaire Walden Schmidt, who buys Charlie’s house after his death.
It is not unusual for producers to cast the same actors across different sitcoms. Sometimes these special appearances are a little bit more obvious, like in the case of Charlie Sheen’s The Big Bang Theory, while others could have easily been overlooked. The Big Bang Theory was also produced by Chuck Lorre and was every bit as successful as its predecessor, airing for 12 seasons from 2007 to 2019. The sitcom followed a group of nerdy socially awkward scientists who befriend a ditzy but street-smart woman who moves in next door. Over the course of the show, several actors made guest appearances, including many who appeared as themselves (such as Carrie Fisher and Mark Hamill). However, some of the actors previously seen on Two And A Half Men also went on to portray different roles on The Big Bang Theory.
Charlie Sheen
Sheen portrayed Charlie Harper, the lead role on Two And A Half Men for the first eight seasons of the show, before getting cut and being replaced by Ashton Kutcher. In The Big Bang Theory, Sheen makes a cameo appearance in season 2, episode 4: “The Griffin Equivalency.” Raj is drinking alone in The Cheesecake Factory when he tells a random man at the bar that he’s going to be in People magazine. The man turns out to be Charlie Sheen who tells Raj to call him when he’s on the cover.
Vernee Watson-Johnson
Character actress Vernee Watson-Johnson, best known for playing Will Smith’s mother in The Big Bang Theory as Althea, a nurse working reception at the High IQ Sperm Bank. She appeared four more times in seasons 4, 5, and 10, and in her final appearance aids in the delivery of Bernadette’s baby. Althea is usually shown to be a sarcastic nurse, judging Sheldon and his friends while addressing their medical issues. On Two and A Half Men, Watson-Johnson appeared as a nurse in season 1 when Charlie takes Jake to the hospital after he hits his head playing basketball, and then twice again in season 9. She also appears in season 12 as an airport check-in counter employee named Karen that Alan attempts to bribe. More recently, she has played Nurse Robinson on two episodes of Young Sheldon.
Brooke D’Orsay
Brooke D’Orsay appeared as Christy Vanderbel, an old friend of Penny’s, in season 1, episode 7: “The Dumpling Paradox." Penny states that Christy is like family because she was engaged to Penny’s cousin while also sleeping with Randall, Penny’s brother. In the episode, she dates Howard on the condition that he buys her things until Mrs. Wolowitz forces him to break up with her. D’Orsay appeared as two separate characters on Two And A Half Men, first as Robin in a season 4 episode, and then as Kate, Walden’s season 10 love interest. Walden meets Kate at the department store she works at while in the persona of a normal guy because he wants to find a girlfriend who doesn't want him for his money. They go on a few dates and Walden invests in her fashion line, pretending that it's Alan’s money.
James Earl Jones
James Earl Jones is best known as the The Lion King. Jones plays himself in a season 7 episode of The Big Bang Theory, where he meets Sheldon at a sushi restaurant and then invites him for a fun night out that includes visiting the carnival, karaoke, and ice cream. He tells Sheldon anecdotes about his life as an actor, and they go to pull a doorbell prank at Carrie Fisher’s house. He also guest stars as himself in Two And A Half Men season 6, episode 11, playing the minister presiding over Charlie’s imagined funeral.
Brian Thomas Smith
Smith portrayed Penny’s on-and-off-again boyfriend Zack Johnson on The Big Bang Theory. Zack is shown as a foil to Leonard and often comes between Leonard and Penny. He is a dim-witted and friendly guy who frequently tries to chat with the guys about science, even though he doesn’t know anything. Zack met Penny because his dad’s company supplied the menus to the Cheesecake Factory, where Penny worked for most of the series. In season 7 it's revealed that Penny married Zack in Las Vegas, but they believed the ceremony was fake and had no idea they were legally married. In Two And A Half Men, Smith briefly appeared as a character named Emmett in season 3, episode 16: “Ergo, the Booty Call.”
Brian Patrick Wade
Brian Patrick Wade portrayed Kurt, another one of Penny’s dumb jock boyfriends, on The Big Bang Theory. He appeared in three episodes in seasons 1 and 2, the first one being the pilot episode in which Penny sends Sheldon and Leonard to bring her TV from Kurt’s apartment, only for them to return without their pants. Wade appears in a season 4 episode of Two And A Half Men as Sam, a lifeguard who saves Charlie from drowning.
Sara Rue
Sara Rue portrayed Dr. Stephanie Barnett, a surgeon Leonard dated briefly in season 2. Howard attempts to date Stephanie by letting her drive the Mars Rover in Season 2, episode 8: “The Lizard-Spock Expansion.” When Howard gets the rover stuck in a ditch, he calls his friends for help, which is how Leonard and Stephanie meet and hit it off. Stephanie is shown to be good at dealing with Sheldon in the subsequent episode, and then in episode 10, Leonard attempts to slow down their relationship when he feels it is moving too quickly. The two break up at some point off-screen before the following episode. Rue portrayed Berta’s daughter in Two And A Half Men. In season 4, Berta introduces Charlie and Alan to her pregnant daughter Naomi. Naomi and Alan date in secret for a while and eventually break up when Naomi gets back together with her baby’s father.
Alessandra Torresani
Torresani played Claire in season 9 of The Big Bang Theory. She meets Raj and Howard at the comic bookstore when she overhears them discussing enlists Raj’s help with the science fiction movie script she’s working on. Though she is just interested in his expertise as an astrophysicist, Raj develops feelings for Claire. They date briefly in season 9, and she appears for one episode in season 10 along with Raj’s other ex-girlfriends. In Two And A Half Men season 12, episode 4, Torresani portrays Kathy, a birth mother whose baby Walden and Alan want to adopt.