Richard O'Brien (born Richard Timothy Smith, 25 March 1942) is an English actor, television presenter, writer and theatre performer, best known for writing the stage musical The Rocky Horror Show (1973), famously adapted into a film in 1975, the longest-running theatrical release in history.

O'Brien was born in Cheltenham, Gloucestershire, England. In 1951, the family emigrated to Tauranga, New Zealand but he moved back to England in 1964. On becoming an actor, he changed his name to Richard O'Brien (his maternal grandmother's surname).

O'Brien presented the 1990–93 Channel 4 game show The Crystal Maze, and voiced Lawrence Fletcher in the Disney Channel animated series Phineas and Ferb (2008–2015; 2025–present) and its two films (2011 and 2020). His other acting credits include Flash Gordon (1980), Spice World (1997), EverAfter (1998), Dark City (1998), Dungeons & Dragons (2000), Elvira's Haunted Hills (2001), and Jackboots on Whitehall (2010).

O'Brien is transgender and identifies himself as third gender and uses he/him pronouns.