Joke thievery is the act of performing and taking credit for comic material written by another person without their consent. This is a form of plagiarism and sometimes can be copyright infringement.

A common epithet for a joke thief is "hack", which is derived from the term, "Hack-neyed" (Meaning, "over used and thus cheapened, or trite").

From the music hall and vaudeville beginnings of stand-up comedy, joke thievery was common as there were few chances that a performer from one area would meet one from another and a single twenty-minute set could sustain a comic for a decade. Most jokes at the time were one-liners and there was little in the way of proof of a joke's origin, but the value of each joke was immeasurable to a comedian.Milton Berle and Bob Hope had a long-standing feud due to Hope's accusation that Milton Berle had stolen some of his jokes. Berle never refuted the claim, but instead embraced the title "The Thief of Bad Gag".

Even the most famous of comics have found themselves, knowingly, or unknowingly, stealing material. Bill Cosby admitted to stealing a joke by George Carlin involving an uneducated football player doing a television commercial. Cosby said that what makes the routine his own is the surreal phrase “little tiny hairs.” Likewise, Carlos Mencia, many years later performed a bit about athletes and their parents that hearkened back to a Cosby bit from his album, Bill Cosby: Himself.

David Cross (born April 4, 1964) is an American actor, writer and stand-up comedian perhaps best known for his work on HBO's sketch comedy series Mr. Show and for his role as Tobias Fünke in the Fox sitcom Arrested Development.

Cross starred in The Increasingly Poor Decisions of Todd Margaret, had main roles in the Comedy Central animated sitcom Freak Show and the Fox sitcom Running Wilde and currently has a recurring role in the ABC sitcom Modern Family.

Cross was born in Atlanta, Georgia, the son of Susi and a father who immigrated from Leeds, England. Six months after his birth, Cross's family moved to Florida. After additional moves to New York and Connecticut, the family settled back in Roswell, Georgia, where Cross remained for nearly a decade. His family was poor and his father left the family when Cross was ten years old, and Cross and his father have not spoken since he was 19, though they both primarily resided in New York City until Cross sold his home there in 2011. Cross and his family were evicted from their home while living in Georgia. He spent some time living in motels and at friends' homes while growing up. He has two sisters, and once bailed his youngest sibling out of jail.

Robin McLaurin Williams (born July 21, 1951) is an American actor and comedian. Rising to fame with his role as the alien Mork in the TV series Mork & Mindy, and later stand-up comedy work, Williams has performed in many feature films since 1980. He won the Academy Award for Best Supporting Actor for his performance in the 1997 film Good Will Hunting. He has also won two Emmy Awards, four Golden Globes, two Screen Actors Guild Awards and five Grammy Awards.

Williams was born in Chicago, Illinois. His mother, Laura McLaurin (née Smith, 1922–2001), was a former model from New Orleans, Louisiana. His father, Robert Fitzgerald Williams (September 10, 1906 – October 18, 1987), was a senior executive at Ford Motor Company in charge of the Midwest region. His maternal great-great-grandfather was senator and Mississippi governor Anselm J. McLaurin. Williams is of English, Welsh, Irish, and French ancestry. He was raised in the Episcopal Church (his mother practiced Christian Science). He grew up in Bloomfield Hills, Michigan, where he was a student at the Detroit Country Day School, and later moved to Woodacre, Marin County, California, where he attended the public Redwood High School. Williams studied at Claremont McKenna College (then called Claremont Men's College) for four years. He has two half-brothers: Todd (who died August 14, 2007) and McLaurin.