Trivia: Born on a Belgian army base, curly brown-haired Johnny Galecki grew up in Chicago and started acting professionally at the age of 12. He made his feature film debut in 1988 as River Phoenix's little brother in A Night in the Life of Jimmy Reardon. He then assumed the role of Rusty Griswold in National Lampoon's Christmas Vacation, and gained his first regular role on a TV series as Robert Ulrich's son in American Dreamer. In 1991, he starred in the made-for-TV movie Backfield in Motion, co-starring the production team of Roseanne and Tom Arnold. The next year, Galecki joined the cast of Roseanne as Darlene's sensitive and put-upon boyfriend David Healy. He stayed on the show until its final season in 1997, although he wasn't on very much during its last few years. His other television credits include several guest appearances, leading roles in made-for-TV movies, and a part on the short-lived Head of the Class spin-off Billy. After Roseanne ended, he got back into features with small parts in I Know What You Did Last Summer, Bean, and Suicide Kings. He continued playing slightly effeminate sensitive males in The Opposite of Sex and Morgan's Ferry. After bit parts in Bounce, Playing Mona Lisa, and Vanilla Sky, Galecki played a leading role in the comedy thriller Bookies, which premiered at the 2003 Sundance Film Festival. In 2007 he landed the leading role in the sitcom The Big Bang Theory and it grew to be one of the most popular shows on TV, earning Galecki Emmy, Golden Globe, and Sag nominations in 2011 for his work on the show. He maintained his movie career in projects such as Hancock and In Time.

Trivia: First noticed by many viewers as Tim -- the Klingon-spouting "knight in training" involved with the mother of Mark (Peter Sarsgaard) in Zach Braff's gently observed comedy drama Garden State (2004) -- American actor Jim Parsons moved from this memorable debut into a sequence of periodic roles in U.S. features. These included Chris Terrio's urban ensemble drama Heights (2004), opposite Glenn Close and Elizabeth Banks, and Brad Silberling's comedy drama 10 Items or Less (2006), opposite Morgan Freeman and Paz Vega. His breakout success came when he was cast as uber-nerd Sheldon on The Big Bang Theory. His work on that show led to him scoring an Emmy win for Outstanding Lead Actor in a Comedy Series, and helped him earn small parts on the big screen in The Big Year and The Muppets.

Trivia: Though initially typecast in comedic roles -- including a small turn in Old School (2003), a contribution to Tracey Ullman in The Trailer Tales (2003), and work on MADtv -- American character actor Simon Helberg quickly branched out into diverse genres. He appeared as a CBS page in George Clooney's revered Edward R. Murrow biopic Good Night, and Good Luck., as a junior agent in Christopher Guest's For Your Consideration (2006), and in a recurring role on the Aaron Sorkin comedy drama Studio 60 on the Sunset Strip. In 2007, Helberg was cast in the regular role of Howard Wolowitz on the sitcom The Big Bang Theory, about a couple of nerdy physicists (Johnny Galecki and Jim Parsons) who struggle with women, and everything else outside the lab. In 2007, Helberg also made appearances in the comedies Mama's Boy and Walk Hard: The Dewey Cox Story. He played a young rabbi in the Coen brothers film A Serious Man (2009), and continued to make guest appearances on TV shows such as Kick Buttowski: Suburban Daredevil and Drunk History, while maintaining his regular status on The Big Bang Theory.

Trivia: Actor Kunal Nayyar first made a splash in Hollywood playing physicist Koothrappali on the series The Big Bang Theory, which debuted on CBS in 2007. In 2012 Nayyar voiced the character of Gupta in Ice Age: Continental Drift, and the following year he could be seen opposite Gina Gershon and Billy Campbell in the thriller, The Scribbler. In addition to his feature work Nayyar also co-wrote the critically acclaimed play Cotton Candy, which runs in New Delhi.

Trivia: Began her career as a comedian and had a one-woman show, The Miss Education of Jenna Bush, in which she played the daughter of former president George W. Bush. Co-wrote, directed and starred in the comedic short The Condom Killer. Toured with the political-satire group Gross National Product. Performs with The Realest Real Housewives show, in which comedians read transcripts from the Real Housewives franchise. Was a recurring guest star on series 3 of The Big Bang Theory before joining the cast as a series regular in series 4.

Trivia: Name means "water" in Hebrew. Had her big break in the 1988 film Beaches, playing the younger version of Bette Midler. Appeared in the music video for Michael Jackson's "Liberian Girl." Made her television debut in the 1980s fantasy series Beauty and the Beast. Best known for her role as the title character in the sitcom Blossom. Was successful in many voiceover roles in animated series, including Kim Possible and Hey Arnold! Appeared on a 2009 episode of What Not To Wear. Her The Big Bang Theory character, Amy Farrah Fowler, is a neurobiologist, corresponding to Bialik's real-life degrees in neuroscience. Is a spokesperson for the Holistic Moms Network and gave birth to her second son at home.

Trivia: Kaley Cuoco began modeling and acting at the tender age of six, when she was cast in the TV movie Quicksand: No Escape. Growing up in front of the camera, the young actress continued to appear as the requisite little girl in movies like Virtuosity and Picture Perfect until she was cast as teenage daughter Bridget on the sitcom 8 Simple Rules. TV would prove to be the actor's bread and butter, and she would go on to star on Charmed, 6Teen, and Monster Allergy, not to mention The Big Bang Theory, a show that earned her legions of fans as Penny, the hot neighbor of two geeky physicists (Johnny Galecki, Jim Parsons). Cuoco also continued to appear in films, though on a much smaller scale compared to her TV work. She appeared in a supporting role in the Easter film Hop in 2011, and played the female lead opposite Kevin Hart and Josh Gad in The Wedding Ringer in 2015.

Trivia: Studied acting with Uta Hagen. Had a recurring role on The Big Bang Theory starting with its second series, and was promoted to series regular in 2012 for the sixth series. Plays the owner of a comic-book shop in The Big Bang Theory, and once worked at a similar establishment in New York City. Both of his parents are schoolteachers. Has appeared in more than 30 US adverts, including Eggos and FedEx.

Trivia: Like her older half-sister Melissa (Little House on the Prairie), actress Sara Gilbert grew up on a television series, in this case, the long-running ABC sitcom Roseanne (1988-1997). She and her sister and her older half-brother, Jonathon Gilbert, are the third generation of a showbiz family. Her grandfather, Harry Crane, was a writer for The Honeymooners, her grandmother, Julia Crane, was a former Miss Brooklyn and a dancer, and her mother is a producer and talent manager. Gilbert made her professional debut in a television commercial at age six, and from there appeared in the television series Tales of the Apple Dumpling Gang (1982). She then played a small role in the made-for-TV movie Calamity Jane, which starred Jane Alexander. Gilbert's career slowed down after that and she did not appear on television until 1988 when she appeared in Runaway Ralph as part of the ABC Weekend Special. As Darlene Connor in Roseanne, Gilbert believably played a cynical, smart-mouthed, but sensitive foil for Roseanne. Gilbert showed versatility as a confused Daddy's girl who is victimized by a calculating Drew Barrymore in Poison Ivy (1989) and as a Southern child with a dark secret who is befriended by a gentle black man in the well-wrought Sudie and Simpson (1990). Gilbert has been twice nominated for an Emmy and has won three Youth in Film Awards. During the last couple seasons of Roseanne, Gilbert began attending Yale University where she studied art and photography. She has also been an avid supporter for various environmental causes through her affiliation with Earth Communications Office (ECO).She stayed away from acting for the most part until 2007 when she began making occasional appearances on the hit sitcom The Big Bang Theory often playing opposite her former Roseanne co-star Johnny Galecki. In 2010, she created the talk show The Talk, a knockoff of The View, and serves as an executive producer and co-host of the series.