A Connecticut Yankee in King Arthur's Court is an 1889 novel by American humorist and writer Mark Twain. The work is a very early example of time travel in literature, anticipating by six years H. G. Wells' The Time Machine of 1895 (however, unlike Wells, Twain does not give any real explanation of his protagonist's travelling in time). Some early editions are entitled A Yankee at the Court of King Arthur.

The novel explains the tale of Hank Morgan, a 19th century citizen of Hartford, Connecticut who awakens to find himself inexplicably transported back in time to early medieval England at the time of the legendary King Arthur in AD 528.

The story itself begins in a first person narrative in Warwick Castle, where a man details his recollection of a tale told to him by a "curious stranger" who is personified as a Knight through his simple language and familiarity with ancient armor.

After a brief tale of Sir Launcelot of Camelot and his role in slaying two giants from the third-person narrative, a man named Hank Morgan enters and, after being given whiskey by the narrator, he is persuaded to reveal more of his story. Described through first-person narrative as a man familiar of the firearms and machinery trade, Hank is a man who had reached a level of super-intendant due to his proficiency in firearms manufacturing, with two thousand subordinates. He describes the beginning of his tale by illustrating details a disagreement with his subordinates, where he sustained a head injury from a "crusher" to the head caused by a man named "Hercules" using a crowbar. After passing out from the blow, Hank describes waking up underneath an oak tree in a rural area of Camelot where a Knight questions him for trespassing upon his land, and after establishing rapport, leads him towards Camelot castle.