Pitkern (also Pitcairnese) is a creole language based on an 18th century dialect of English and Tahitian. It is a primary language of Pitcairn Island with fewer than 100 speakers worldwide. However, the closely related Norfuk language has a few thousand native speakers. Pitkern and Norfuk are unusual in that, although their home islands are located in the Pacific Ocean, they have been described as Atlantic creoles.

Following the Mutiny on the Bounty, the British mutineers stopped at Tahiti and took 18 Polynesian people, mostly women, to the remote island of Pitcairn and settled there with them. Initially, the Tahitians spoke little English and the Bounty crewmen knew even less Tahitian. Isolated from the rest of the world, they had to communicate with each other. Over time, they formed a unique new language which blended a simplified English with Tahitian words and speech patterns.

Pitkern was influenced by the diverse English dialects and accents of the crew. Geographically, the mutineers were drawn from as far as the West Indies, with one mutineer being described as speaking a forerunner of a Caribbean patois. One was a Scot. At least one, the leader Fletcher Christian, was a well-educated man, which at the time made a major difference in speech. Both Geordie and West Country have obvious links to some phrases and words, such as "whettles", meaning food, from "victuals".

Many expressions which are not commonly used in the modern English that is spoken in most areas of the world carry on in Pitkern. These expressions include words from British maritime culture in the age of sailing ships. The influence of Seventh-day Adventist Church missionaries and the King James Version of the Bible are also notable.

In the mid 19th century, the people of Pitcairn resettled on Norfolk Island. Later some moved back. Most speakers of Pitkern today are the descendants of those who went back. Many stayed on Norfolk as well, where the closely related language Norfuk is still spoken. Pitkern and Norfuk are mutually intelligible, and are sometimes considered the same language.