Puck

Puck was a character from a play by William Shakespeare which was produced at some point prior to The Tempest.

In his working notes for The Tempest, Shakespeare wrote a reminder to himself to check if the Puck costume was still in the stores. Later, he mistakenly referred to Puck in place of the character Ariel three times, necessitating that Shakespeare cross out Puck's name and replace it with Ariel's on each occasion. (PROSE: The Tempest – A Work in Progress)

Behind the scenes
Puck is from the play A Midsummer Night's Dream, although The Tempest – A Work in Progress falls short of stating that explicitly. One of the times Shakespeare mistakes Ariel for Puck is when noting Ariel's invisibility, going on to suggest to himself that he reuse his "people-being-pinched-by-invisible-attacker gag" from A Midsummer Night's Dream, alluding to the connection.