Career: Harmon's first TV appearance came as a child in an advert alongside his father. His break into came via a 1975 episode of Police Woman. His CV includes everything from glossy soaps such as Flamingo Road, to big-screen offerings, including Beyond the Poseidon Adventure and The Presidio. He gained much acclaim for his role in medical drama St Elsewhere, playing a doctor who contracted HIV; he was named People magazine's Sexiest Man Alive while appearing on the show. He also featured in the films Freaky Friday, Chasing Liberty and TV series The West Wing and JAG. These days he's best known for his role as agent Leroy Jethro Gibbs in NCIS, a part he's played since 2003.

Career: Alexander's first films were low-budget offerings which enabled her to hone her acting skills. Although projects such as Visceral Matter, Battle of the Sexes and Twin Falls Idaho didn't do well at the box office, they did get her noticed. It was TV series Dawson's Creek, in which she played Gretchen, that made her a familiar face when she joined the cast in 2001. Since then, Alexander has appeared in a number of productions, including All Over the Guy, CSI: Crime Scene Investigation, Friends, Mission: Impossible III and NCIS. She also wrote, produced and starred in the movie Lucky 13 in 2005. She is currently starring in the American crime drama Rizzoli & Isles.

Career: Weatherly's first TV appearance coincided with a part in the independent film Trigger Happy, which was swiftly followed by a number of small-screen appearances. He moved to Los Angeles, where he was given the lead in the series Significant Others. A meeting with director Whit Stillman led to his scooping a plum role in The Last Days of Disco, and TV work in the comedy show Jesse. More film and TV roles followed, and in 2000 he landed the part of Logan Cale in James Cameron's sci-fi series Dark Angel, as well as a big-screen appearance in the film Gun Shy. Recent work includes the crime drama show NCIS, and movies The Mystery of Natalie Wood and Her Minor Thing.

Career: After picking up work in commercials and music videos, Perrette landed a role in US crime drama Murder One. She's since popped up in The Drew Carey Show, Jesse, That's Life, Early Edition, Frasier, Dawson's Creek, 24, CSI and Veronica's Closet. She took the lead in the 1997 big screen romance The Price of Kissing. In 2003, she landed the role of Abby Sciuto in TV series JAG, and she now plays the character in the JAG spin-off NCIS. She has also appeared in the film I Am Bad.

Career: McCallum became an assistant stage manager, but National Service interrupted his career. He made his film debut in 1957's These Dangerous Years, and appeared in numerous British movies before moving to Hollywood in the early 1960s. He landed roles in Billy Budd and The Great Escape but it was his performance as Illya Kuryakin in The Man from UNCLE that made him a household name in 1964. The series ran until 1968, and a spin-off TV movie was made in 1983. He also released four albums in the 1960s. Other major projects include Colditz, The Invisible Man, Sapphire and Steel, Mother Love, Hear My Song, and Cluedo. Since 2003, he has starred in popular American drama NCIS, playing forensics expert Dr Donald 'Ducky' Mallard.