The Big Bang Theory

Johnny Galecki portrays Leonard Hofstadter, a socially inept physicist who often serves as the straight man to his friends' eccentric behaviors. Leonard is intelligent and has a somewhat low self-esteem. He develops an on-again, off-again romantic relationship with Penny throughout the series.

Jim Parsons plays Sheldon Cooper, a highly intelligent but socially inept physicist with obsessive-compulsive tendencies. Sheldon often struggles with social interactions and has a love for routine and order. His unique personality and quirks provide much of the show's humor.

Kaley Cuoco portrays Penny, a beautiful and outgoing aspiring actress who lives across the hall from Leonard and Sheldon. Penny is often the voice of reason and offers a contrasting perspective to the group's nerdy interests. Throughout the series, she forms close friendships with the main characters.

Simon Helberg plays Howard Wolowitz, a brilliant aerospace engineer with an overbearing and somewhat creepy personality. Howard is known for his distinctive fashion choices and his obsession with women. He is in a long-term relationship with Bernadette and together they have children.

Kunal Nayyar portrays Rajesh Koothrappali, an astrophysicist who initially struggles with selective mutism, making it difficult for him to talk to women. Raj eventually overcomes his condition and forms romantic relationships throughout the series. He is known for his calm and gentle demeanor.

Melissa Rauch plays Bernadette Rostenkowski, a microbiologist who later becomes Howard's wife. Bernadette has a high-pitched voice and a strong personality. Despite her small stature, she is not afraid to assert herself and often provides comedic moments with her feistiness.

Mayim Bialik portrays Amy Farrah Fowler, a neurobiologist who becomes Sheldon's love interest. Amy is highly intelligent, socially awkward, and shares many quirks with Sheldon, making her a good match for him. Throughout the series, her character undergoes significant personal growth.

Travis Schuldt guest stars as Eric, Penny's ex-boyfriend. Eric appears in a few episodes, providing some romantic tension and comedic moments with his interactions with the main characters.