Dumb and Dumber is a 1994 American buddy comedy film directed by Peter Farrelly, who cowrote the screenplay with Bobby Farrelly and Bennett Yellin. It is the first installment in the Dumb and Dumber franchise. Starring Jim Carrey and Jeff Daniels, it tells the story of Lloyd Christmas (Carrey) and Harry Dunne (Daniels), two dumb but well-meaning friends from Providence, Rhode Island, who set out on a cross-country trip to Aspen, Colorado, to return a briefcase full of money to its owner, thinking it was abandoned as a mistake though it was actually left as a ransom. Lauren Holly, Karen Duffy, Mike Starr, Charles Rocket, and Teri Garr play supporting roles.

The film was released on December 16, 1994. It grossed $247 million at the box office and has developed a cult following in the years after its release and is regarded as one of the best comedies of the 1990s. The success of Dumb and Dumber launched the career of the Farrelly brothers, established the range of the heretofore dramatically acclaimed Daniels as a gifted comedic actor and revitalized his Hollywood career, and solidified Carrey's reputation as one of the most prominent actors of the 1990s. The film also spawned an animated TV series, a 2003 prequel, and a 2014 sequel.