Career: Four years later, he landed what would become his big break - the role of David in hit comedy series Roseanne. He played the articulate but unworldly lad for five years. This led to a series of similar parts, this time on the big screen, in movies such as I Know What You Did Last Summer and The Opposite of Sex. His CV also includes appearances in Vanilla Sky, My Name is Earl, Hancock and Table for Three. In 2006, he took to the stage in a Broadway production of The Little Dog Laughed (which also featured his first nude scene). He returned to the small screen for the sitcom The Big Bang Theory.

Career: Early in his career, Parsons worked on Off-Broadway productions and appeared on TV several times. He had a recurring role on Judging Amy, appeared on the TV series Ed and had minor roles in such films as Garden State (2004) and School for Scoundrels (2006). His big break came when he landed the role of Sheldon Cooper in The Big Bang Theory, a role that earned him four Primetime Emmy Awards for Outstanding Lead Actor in a Comedy Series and a Golden Globe for Best Performance by an Actor in a Television Series - Comedy or Musical. He went on to appear in the films The Big Year (2011), The Muppets (2011), Home (2015) and Hidden Figures (2016).

Career: Shatner spent years as a jobbing actor, appearing in such movies as The Brothers Karamazov and The Intruder, as well as The Twilight Zone TV series before Star Trek made him a household name in 1966. He played Captain Kirk for three years before the show was cancelled, then appeared in numerous TV shows and movies before Star Trek: The Motion Picture relaunched his career in 1979. He starred as Kirk in six more films before the character was finally killed off in 1994. He has also featured in TJ Hooker, Free Enterprise and Miss Congeniality and its sequel. Shatner returned to TV in 2004 in the series Boston Legal. In 2010, he starred in his first sitcom, $#*! My Dad Says. Away from showbusiness, he's written several sci-fi novels, recorded a number of much-criticised albums and is a champion horse breeder.

Career: Smith's second film, Mallrats (1995), had a $6million budget but it was a box-office flop. He bounced back in 1997 with the romantic comedy Chasing Amy. His career since then has been hit-and-miss. His credits include Dogma (1999), Jay and Silent Bob Strike Back (2001), Jersey Girl (2004), Clerks II (2006) and Zack and Miri Make a Porno (2008).

Career: After graduating from Carnegie Mellon, Manganiello moved to Los Angeles, California and gained his first film role in Spider-Man (2002). He had various parts on such TV series as ER, How I Met Your Mother and One Tree Hill before landing the role of Alcide Herveaux in fantasy horror series True Blood. Since then, he has had roles in a number of films, including What to Expect When You're Expecting (2012), Sabotage (2014), Magic Mike (2012) and its sequel Magic Mike XXL (2015). Manganiello is also a published author, having released his first book, Evolution, in late 2013.