Robert John Downey, Jr. (born April 4, 1965) is an American actor who made his screen debut in 1970 at the age of five, appearing in his father's film Pound, and has worked consistently in film and television ever since. During the 1980s, he had roles in series such as coming of age films associated with the Brat Pack. His role in Less Than Zero (1987) was the first time Downey's acting would be commended by critics. After Zero, Downey was cast in starring roles in bigger films, such as Air America (1990), Soapdish (1991), and Natural Born Killers (1994). He played Charlie Chaplin in the 1992 film Chaplin, for which he received an Academy Award nomination for Best Actor.

Between 1996 and 2001, Downey was frequently arrested on drug-related charges. After being released from the California Substance Abuse Treatment Facility and State Prison in 2000, Downey joined the cast of the hit television series Ally McBeal playing the new love interest of Calista Flockhart's title character. His performance was praised and received accolades, but his character was written out when Downey was fired after two drug arrests in late 2000 and early 2001. After one last stay in a court-ordered drug treatment program, Downey finally achieved lasting sobriety and his career began to take off again. He appeared in semi-independent films such as The Singing Detective (2003), Kiss Kiss Bang Bang (2005), and A Scanner Darkly (2006). He also had supporting roles in the mainstream films Gothika (2003) and Zodiac (2007). In 2004, Downey released his debut studio album The Futurist.

In 2008, Downey was cast as the title character in the comic book adaptation Iron Man. The film was a huge success, and its opening weekend is still in the top 25 openings of all time.He reprised the role in three other films set within the Marvel Cinematic Universe, The Incredible Hulk (2008), Iron Man 2 (2010), and Marvel's The Avengers (2012), and will again in the upcoming third film of the planned Iron Man trilogy, Iron Man 3, due to open in 2013. Downey's other 2008 films included Charlie Bartlett and the Ben Stiller-directed Tropic Thunder, the latter of which he was nominated for the Academy Award for Best Supporting Actor. Downey also starred as fictional British detective Sherlock Holmes in Guy Ritchie's Sherlock Holmes and its follow-up Sherlock Holmes: A Game of Shadows, released Christmas 2009 and late December 2011, respectively. Soon after Sherlock Holmes, Downey won a Golden Globe for Best Performance by an Actor in a Motion Picture – Musical or Comedy for that portrayal of the famous detective.