Beginning back in 2007, Big Bang Theory made a big splash with fans who couldn't get enough of the relationship between Dr. Sheldon Cooper and...well, pretty much everyone. For 12 seasons, we've watched Sheldon grow into a man who was capable of affectionate feelings, Penny and Leonard grow closer and closer, Howard and Bernadette having a family, and Raj being Raj. These co-workers and best friends taught us a lot about their brainy world, and fans were just happy to be apart of the ride.
Throughout the halls of Caltech and streets of Pasadena, California, we were also introduced to a handful of guest stars; guest stars who are way more famous than their small appearance on the show. Throughout 12 seasons and 12 years, we're taking a look at 10 guest stars we forgot appeared on The Big Bang Theory.
10 Judd Hirsch
Appearing in one episode in the ninth season as Dr. Alfred Hofstadter, actor Judd Hirsch starred as Leonard's successful dad. Although his dad is mentioned often throughout the seasons, we've never actually met him until Leonard and Penny decide to have a wedding in front of their friends and family.
In this episode, we got to finally see Leonard's dad interact with his ballsy mother, who has ripped his name to shreds every chance she got when she was on screen. In real life, Hirsch has been in the likes of Independence Day, The Good Wife, A Beautiful Mind, and more.
9 Charlie Sheen
When one thinks of The Big Bang Theory, they don't necessarily think of actor (and former hot mess) Charlie Sheen. However, in the second season, Chalie's face popped up in "The Griffin Equivalency" when Raj is invited to be in People Magazine. As he's bragging about his accomplishment at the Cheesecake Factory, Charlie swirls around in his chair and says to call him one day if he ever makes it on the cover. This, of course, is in reference to Charlie being a tabloid king. But considering Chuck Lorre directed both Two and a Half Men and The Big Bang Theory, the connection makes sense.
8 Laurie Metcalf
Sheldon's mother Mary may have appeared in more episodes than the average guest star but it's fun to remember just how much of a big deal Laurie Metcalf is! I mean, she's the voice of Andy's mom in Toy Story for Heaven's sake! She's also been on Rosanne, Getting On, Desperate Housewives, and dozens more in her decades-long career.
In The Big Bang Theory, Mary is the super religious mother of Sheldon Cooper. She lives in Texas where she always makes sure to call her baby boy when things are troubling him. With his love for science and her love for God, these two have hilariously awkward conversations.
7 Jerry O'Connell
It was a surprise to everyone when we finally had the chance to meet Sheldon's brother George Cooper Jr. in season 11. We've heard about he and Sheldon's twin sister for years but never had the chance to see the two interact. However, Sheldon appears in George's store to make amends for all the bad blood over the past couple of years. It was then we had a chance to see George's side of things and why he disliked his brother so much. Thankfully, Sheldon sees his side and apologizes, and George decides to attend Sheldon's wedding. Portraying George, however, was none other than Jerry O'Connell!
O'Connell is most known for his hit '80s movie Stand by Me, but he should also be noted for Billions and for doing voice work for video games.
6 Eliza Dushku
In the seventh episode of season four, Howard is extremely close to getting the opportunity to go to outer space. The FBI decides to send their agent, Angela Paige (Dushku), over to meet Howard's closest friends and colleagues to gather information on his character, and of course, it goes horribly. Eliza Dushku portrays the agent who makes Raj feel uncomfortable simply by being female, slams Leonard's flirting down to the ground, and got way too much information out of Sheldon. In all, she was a tough FBI agent.
Off set, Eliza Dushku is most known as Missy in Bring It On, but she's also been on the TV series Hulk and the Agents of S.M.A.S.H., Tru Calling, and Buffy the Vampire Slayer.
5 JUDY GREER
Judy Greer has been in everything from Ant-Man, 13 Going On 30, Modern Family, and yes, even The Big Bang Theory. She's one of those actresses that seems to always pop up from time to time. On the show, however, she portrays Dr. Elizabeth Plimpton — a friend of Sheldon's. In the third episode, she's staying with Sheldon and Leonard for a work-related trip but ends up sleeping with Leonard (and Raj). As it turns out, this doctor was a tad promiscuous and it rubbed Penny the wrong way since she and Leonard just broke up. Greer did play an amazing part who was both extremely intelligent and sexy.
4 OCTAVIA SPENCER
Octavia Spencer is such a serious actress, it's almost comical that she was a guest star in anything and not one of the leads! Nevertheless, she did appear as a clerk at the DMV in episode five in the second season. This Oscar winner had to deal with Sheldon's antics after he had a few questions about the exam. And like most people who deal with Sheldon, she got sick of his trying questions and told him to leave.
When not working at the DMV, Spencer has been in incredible films like The Help, Hidden Figures, and The Shack.
3 SUMMER GLAU
"It's hot in here, it must be summer." This is what Howard was preparing to say to actress Summer Glau as he saw her taking the train. Raj took his thunder, though, and used the pickup line himself. Unlike some of the other guest stars, Summer played herself so that the gang could fan-girl over her. She was a good sport hanging with Howard and Raj but over time, she grew sick of Howard being so forward. Eventually, she escaped the group and got off the train.
Off the set of The Big Bang Theory, Glau has been on Grey's Anatomy, Terminator: The Sarah Connor Chronicles, Arrow, and more!
2 DANICA MCKELLAR
Danica McKellar is most known for starring in The Wonder Years, but she's still acting in 2019, appearing in a ton of TV movies and shows. On Big Bang, though, she appeared in the 12th episode of season three when she decides to go on a date with Raj. The pair met a mixer when Raj forced Sheldon to be his wingman. While many thought this idea would blow up in smoke, it actually worked since McKellar's character had a friend who was totally into Sheldon.
1 GEORGE TAKEI
The amazing thing about The Big Bang Theory is that guest stars from various "geeky" shows and movies pop up from time to time. In one instance, Star Trek's George Takei appeared in season four as an imaginary friend to Howard.
In the episode, Howard would much rather spend his nights with an imaginary Katee Sackhoff than a real-life Bernadette. To bring him back to life, George Takei appears and tries to bring insight.
In his early 80's, Takei is still taking Hollywood by storm with two projects being wrapped up this year and in 2021.