Malvolio

A "servant" was a character in William Shakespeare's play Twelfth Night.

While outlining the play in a meeting with Richard Burbage and the Fifth Doctor, specifically the character of Sir Toby Belch, Shakespeare said Belch would be "in conflict with the upright servant" of the woman in love with Viola and "make it seem that the officious servant [was] mad for love of his mistress". (PROSE: Diary Extract)

Behind the scenes
Although not named in Diary Extract, the character is a clear reference to Malvolio.