Robert John Downey Jr. (born April 4, 1965) is an American actor and singer. His career has included critical and popular success in his youth, followed by a period of substance abuse and legal troubles, and a resurgence of commercial success in middle age. For three consecutive years from 2012 to 2015, Downey topped the Forbes list of Hollywood's highest-paid actors, making an estimated $80 million in earnings between June 2014 and June 2015.

Making his acting debut at the age of five, appearing in his father's film Pound (1970), Downey Jr. appeared in roles associated with the Brat Pack, such as the teen sci-fi comedy Weird Science (1985) and the drama Less Than Zero (1987). He starred as the title character in the 1992 film Chaplin, which earned him a nomination for the Academy Award for Best Actor and won him the BAFTA Award for Best Actor in a Leading Role. After being released in 2000 from the California Substance Abuse Treatment Facility and State Prison where he was on drug charges, Downey joined the cast of the TV series Ally McBeal playing Calista Flockhart's love interest. This earned him a Golden Globe Award. His character was written out when Downey was fired after two drug arrests in late 2000 and early 2001. After his last stay in a court-ordered drug treatment program, Downey achieved sobriety.

Downey Jr.'s career prospects improved when he featured in the black comedy crime Kiss Kiss Bang Bang (2005), the mystery thriller Zodiac (2007), and the satirical action comedy Tropic Thunder (2008); for the latter he was nominated for an Academy Award for Best Supporting Actor. Beginning in 2008, Downey began portraying the role of Marvel Comics superhero Iron Man in the Marvel Cinematic Universe, appearing in several films as either the lead role, member of an ensemble cast, or in a cameo. Each of these films, with the exception of The Incredible Hulk, has grossed over $500 million at the box office worldwide; four of these"The Avengers, Avengers: Age of Ultron, Iron Man 3 and Captain America: Civil War"earned over $1 billion, while Avengers: Infinity War earned over $2 billion.

Downey Jr. has also played the title character in Guy Ritchie's Sherlock Holmes (2009), which earned him his second Golden Globe win, and its sequel (2011), both of which have earned over $500 million at the box office worldwide.

As of 2018, the U.S. domestic box-office grosses of Downey Jr.'s films total over US $4.8 billion, with worldwide grosses surpassing $11.2 billion, making Downey Jr. the third highest-grossing U.S. domestic box-office star of all time.