Superior Saturday

Superior Saturday is the primary antagonist of The Keys to the Kingdom series by Garth Nix. Though she falls short under Lord Sunday's rule, she is responsible for all the problems the protagonists encounter throughout the series. However, she makes her first true appearance in book 6, which is named after her. Her main goal is to burst a hole into the Incomparable Gardens, Sunday's domain, and overthrow Sunday and become the most powerful Denizen in The House. She has a bitter envy for Lord Sunday, which is her sin - she thinks because she is the oldest Denizen in The House she should be ruler. She is deceased.

Role
Saturday is first mentioned in book 3 when Arthur mistakes Saturday for a male, and one of the Raised Rats replying that "Superior Saturday is female, as far as we know". Her antagonizing becomes most rapid throughout book 5, where she is causing trouble wherever she can, including locking off all the House's doors and elevators to prevent escape or entrance.

Saturday makes her first full appearance in book 6, where she is revealed to control all of the Upper House. Near the climax of the book, she finally achieves her goal of bursting through the Incomparable Gardens, and in the following book (and the finale) she begins a four way fight between Arthur, Lord Sunday, herself and The Piper and their forces. She is killed by The Piper by being decapitated.

Appearance
Saturday is described as a tall, beautiful woman with long, flowing blue hair and a golden circlet on her forehead, similar to an Egyptians.