A stock character is one that is a recurring character that is recycled in many plays, such as a ladies' maid, as is Maria in Shakespeare's Twelfth Night. Such a character would be likely to show up in any play that dealt with interaction between the upper and lower classes. What makes Maria different, however, is the fact that her personality and actions are anything but those of a stock character. She is vital to the plot, as it is her wit and intelligence that hatch the plot against Malvolio. She is far smarter than her companions, Sir Andrew and Sir Toby, and she is clever enough to pull off a complicated scheme. She is educated enough to forge her lady's handwriting and style well enough to fool Malvolio, who thinks he is her better. And, she is fearless and no-nonsense enough to deal with both the upper and lower class characters in the play in any situation.