"The Big Bang Theory" is a widely successful sitcom on air for 12 seasons. The show revolves around a group of socially awkward scientists and their love interests. One of the show's highlights was the appearance of guest stars, who brought their charm and charisma to the already delightful cast. This article looks at the best guest stars on "The Big Bang Theory," ranked according to their performances.

Brent Spiner

Brent Spiner, known for his role as Data in "Star Trek: The Next Generation," guest appeared on "The Big Bang Theory." He played himself in an episode where he interacted with Sheldon, who was a big fan of his work. The episode featured humorous exchanges between the two characters, and Spiner's cameo delighted fans of "Star Trek" and "The Big Bang Theory."

Paramount/ Gamesradar | Spiner's acting career began with a bit part in Stardust Memories (1980)

Bob Newhart

Bob Newhart, the iconic comedian and actor, made a memorable cameo appearance on "The Big Bang Theory" as Professor Proton. In his recurring role, Newhart's character served as a childhood science show host who significantly influenced the main characters. Newhart's deadpan humor and comedic timing brought laughs to the show, and his interactions with Sheldon were particularly memorable.

Bill Gates

Bill Gates, the co-founder of Microsoft and tech magnate, made a surprise cameo on "The Big Bang Theory." In the episode, the characters had the chance to meet Gates during a trip to a tech conference. Gates' appearance brought a touch of real-world tech industry authenticity to the show and added to the excitement of the storyline.

Channel 4/ AP | Stephen Fry's career is one of the most multifaceted that has ever emerged

Stephen Fry

Acclaimed British actor and comedian Stephen Fry had a guest appearance on "The Big Bang Theory." He played Dr. Stephen Hawking's fictional rival, Dr. Alfred Hofstadter, Leonard's father. Fry's wit and charm brought a new dynamic to the show, and his scenes with the characters provided both humor and emotional depth.

Wil Wheaton

Wil Wheaton, known for his role as Wesley Crusher in "Star Trek: The Next Generation," played an exaggerated version of himself on "The Big Bang Theory." Wheaton portrayed a recurring nemesis of Sheldon's, creating a humorous rivalry between the characters. His appearances on the show showcased his comedic talents and added an extra layer of geeky references.

Nerd HQ/ Wikimedia | Nathan Fillion has been a professional actor since 1993

Sarah Michelle Gellar

Sarah Michelle Gellar, the actress famous for her role as Buffy Summers in the television series "Buffy the Vampire Slayer," appeared on "The Big Bang Theory." In the episode, she played a potential love interest for Raj, one of the main characters. Gellar's cameo brought a touch of romance and excitement to the show, capturing the attention of both fans of "Buffy" and "The Big Bang Theory."

Nathan Fillion

Nathan Fillion, known for his roles in the television series "Firefly" and "Castle," had a cameo on "The Big Bang Theory." He played himself in an episode where he interacted with the characters during a comic book store event. Fillion's appearance delighted fans of his previous work and added to the show's celebration of geek culture.