Little John was the name of a character in Human mythology. Living in 12th century England, he was a member of the Merry Men, a band of outlaws led by Robin Hood who made their home in Sherwood Forest.
In 2367, the entity known as Q transported the senior officers of the USS Enterprise-D into a recreation of Sherwood Forest and the story of Robin Hood in an attempt to teach Captain Picard a lesson about love. During the reenactment, each of the officers played the part of one of the Merry Men. The role of Little John was played by Commander Riker. (TNG: "Qpid")