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: 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: 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: 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: 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: 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: Best known for his trademark deadpan delivery and behind-the-mic evocations of the stoner mentality, Sacramento-born stand-up comedian, character actor, and television mainstay Brian Posehn graduated from Sonoma Valley High School in 1984 before cultivating his schtick at age 21 as a "road comic" in contests across the country and with appearances on MTV's 1/2 Hour Comedy Hour. Many small-screen turns followed, including bit parts on Seinfeld (as Artie, a patient in the episode where Kramer "contracts" gonorrhea) and Friends. In two roles with a slightly higher profile, Posehn joined the Mr. Show sketch comedy troupe on HBO and became a periodic fixture on NBC's Just Shoot Me, as mail clerk Kevin Liotta. Posehn occasionally contributed as well to Comedy Central's Jerky Boys-like puppetcast Crank Yankers. A handful of big-screen roles followed, including that of a store clerk in the yuk-yuk (Jim Carrey-less) comedy sequel Dumb and Dumberer (2003), Jimmy in Rob Zombie's 2005 splatterfest The Devil's Rejects, and a spot as himself in Sarah Silverman: Jesus Is Magic. As an offshoot of Mr. Show, Posehn teamed with Bob Odenkirk and many others to co-author the script of 2002's Run Ronnie Run!, a project intended for the big screen (ala Jackass: The Movie) but disastrously reedited and all but disowned by its creators. Following The Devil's Rejects, Posehn signed on to provide a voice for helmer Mr. Lawrence's second directorial outing (which Rob Zombie scripted), 2007's animated The Haunted World of El Superbeasto. He had some prior experience, via his voice work on a number of animated series, including Mission Hill, 3 South, and several Adult Swim projects. Something of an underground, counterculture figure, Posehn -- a self-proclaimed "metal head" and comic-book devotee -- is good friends with the gifted Southern California-based comic Patton Oswalt (whom he joined on the Comedians of Comedy tour) and, more tellingly, with Anthrax's Scott Ian (with whom he collaborated on the tongue-in-cheek song, "Metal by Numbers.") Posehn has been married to comic Melanie Truhett since 2004.

Trivia: Though her resumé encompasses dozens of supporting roles, more viewers -- many more -- know supporting actress Pamela Adlon (née Segall) through her prolific voice work than by her visage. Like Nancy Cartwright, this spunky and versatile brunette actress is perhaps most familiar for giving breath to a male animated character: that of Bobby Hill, the sweet-natured preteen son of redneck Hank Hill, with dreams of becoming a prop comic, on Mike Judge's family-oriented animated sitcom King of the Hill (1997). Adlon kick-started her career on a low yet memorable note, as Dolores Rebchuck, kid sister of "T-Bird" Paulette Rebchuck (Lorna Luft) in the clunker Grease 2 (1982). Roles in mostly forgettable features such as The Fantastic World of D.C. Collins (1984) and Gate II: Return to the Nightmare (1992), followed through the '80s and '90s, as did guest-starring appearances on sitcoms including The Jeffersons and Night Court. Adlon's fortunes began to improve with the Cameron Crowe-directed Gen-X favorite Say Anything... (1989) and with a vocal turn in Ferngully: The Last Rainforest (1992) that paved the way for her work on King four years later. She and the rest of the cast remained with King of the Hill for many seasons, a testament to that program's enduring popularity. Alongside King, Adlon delivered a fine comic portrayal as Kim, wife of Louis C.K.'s character, on the sitcom Lucky Louie. That series folded after one season, but Adlon soon found her way back to premium cable, with the recurring role of Marcy Runkle, wife talent agent Charlie Runkle (Evan Handler) -- whose star client and best friend was writer Hank Moody (David Duchovney) -- on the successful Showtime dramedy Californication, which premiered in 2007.