Friday is one of the main characters of Daniel Defoe's 1719 novel Robinson Crusoe. Robinson Crusoe names the man Friday, with whom he cannot at first communicate, because they first meet on that day. The character is the source of the expression "Man Friday", used to describe a male personal assistant or servant, especially one who is particularly competent or loyal. Current usage also includes "Girl Friday".
Robinson Crusoe spends twenty-eight years on an island off the coast of Venezuela with his talking parrot Poll, his pet dog, and a tame goat as his only companions. In his twenty-fifth year, he discovers that Carib cannibals occasionally use a desolate beach on the island to kill and eat their captives.
Crusoe observes one of the Caribs, kept captive and about to be eaten, escape his captors. Crusoe ambushes two pursuers, and the others leave in their canoes without knowing what happened to their companions. The escaped captive bows in gratitude to Crusoe, who decides to employ him as a servant. He names him Friday after the weekday upon which the rescue takes place.
Crusoe describes Friday as being a Native American, though very unlike the Indians of Brazil and Virginia. His religion involves the worship of a mountain god named Benamuckee, officiated over by high priests called Oowokakee. Crusoe learned a few of his native words that have been found in a Spanish-Térraba (or Teribe) dictionary, so Friday may have belonged to that tribe, also called the Naso people. Friday tolerates cannibalism, and even suggests eating the men Crusoe has killed.
Crusoe teaches Friday the English language and converts him to Christianity. He tells him that cannibalism is wrong. Friday accompanies him in an ambush in which they save Friday's father.
Crusoe returns to England twenty-eight years after being shipwrecked on the island, and four years after rescuing Friday. Friday's father goes with a Spanish castaway to the mainland to retrieve fourteen other Spanish castaways, but Crusoe and Friday depart the island before they return.
Friday accompanies Crusoe home to England, and is his companion in the sequel The Farther Adventures of Robinson Crusoe, in which Friday is killed in a sea battle.
In Jules Verne's L'École des Robinsons (1882), the castaways rescue an African man on their island who says his name is Carefinotu. T. Artelett proposes to call him Mercredi ("Wednesday"), "as it is always done in the islands with Robinsons," but his master Godfrey prefers to keep the original name.