Pirates of the Caribbean: On Stranger Tides is a 2011 American fantasy swashbuckler film directed by Rob Marshall and produced by Jerry Bruckheimer, from a screenplay by the writing team of Ted Elliott and Terry Rossio. The fourth installment in the Pirates of the Caribbean film series, it is a stand-alone sequel to At World's End (2007) and is loosely based on the 1987 novel On Stranger Tides by Tim Powers. The film stars Johnny Depp, Geoffrey Rush, and Kevin R. McNally, who reprise their roles from the previous films, alongside Penélope Cruz, Ian McShane, Sam Claflin and Àstrid Bergès-Frisbey. The story follows the eccentric pirate Captain Jack Sparrow on a quest for the Fountain of Youth after crossing paths with Angelica, a mysterious woman from his past, and being forced aboard the Queen Anne's Revenge, the ship of the legendary pirate Blackbeard. Jack contends with zombies, mermaids, the Spanish Armada and an uneasy alliance with rival Hector Barbossa, now a privateer of the British Navy.

On Stranger Tides was produced by Walt Disney Pictures and Jerry Bruckheimer Films, and distributed by Walt Disney Studios Motion Pictures. During the back-to-back production of Dead Man's Chest (2006) and At World's End, writers Elliott and Rossio first learned of Powers' novel and considered it a good starting point for a new film in the series. Pre-production started after the end of the 2007–2008 Writers Guild of America strike, with Depp collaborating with the writers on the story design. Gore Verbinski did not return as director from previous films due to his commitment with Rango (2011). Principal photography lasted for 106 days between June and November 2010, with locations in Hawaii, the United Kingdom, Puerto Rico and California. Filming employed 3D cameras similar to those used in the production of the 2009 film Avatar, and ten companies were involved with the film's visual effects. Following inflated production costs which ballooned the net budget to $379 million, the film was the most expensive film ever made at the time of its release.

On Stranger Tides was released in the United States on May 20, 2011, to mixed reviews from critics. The film broke many box office records and was the third highest-grossing film of 2011. A fifth film, Dead Men Tell No Tales, was released on May 26, 2017.