Agatha Wooster (sister of Dahlia, George Wooster [Lord Yaxley], and Bertie's late father), human snapping turtle who has savaged Bertie incessantly from childhood up, living at Woollam Chersey, Herts, and married to Spenser Gregson in Extricating Young Gussie (where her family name is Mannering-Phipps) and stories of the twenties (in Without the Option and Helping Freddie she is called Mrs. Spenser); by The Code of the Woosters he is "the late" Spenser Gregson. Her son Thomas Gregson, a pestilential schoolboy, is under Bingo Little's tutelage in Jeeves and the Impending Doom. Marries Lord Worplesdon about eighteen months before Joy in the Morning; lives with him in Steeple Bumpleigh, Essex in Joy in the Morning, The Mating Season, and thereafter. Kills rats with her teeth, devours her young, eats broken bottles, and turns into a werewolf at the time of the full moon. Tall and thin, about 5' 9" topped off with a beaky nose, an eagle eye, and a lot of grey hair, looks rather like a vulture in the Gobi desert. Cold and haughty, though presumably she unbends a bit when conducting human sacrifices at the time of the full moon, as she is widely rumored to do. Doesn't like Jeeves.

• Aunt Agatha Takes the Count (Aunt Agatha Speaks Her Mind/Pearls Mean Tears)
• Scoring Off Jeeves (The Pride of the Woosters is Wounded/The Hero's Reward)
• Sir Roderick Comes To Lunch (Introducing Claude and Eustace/Sir Roderick Comes To Lunch)
• The Delayed Exit of Claude and Eustace
• Jeeves and the Impending Doom
• Jeeves and the Yule-Tide Spirit
• Episode of the Dog McIntosh
• Indian Summer of an Uncle
• The Code of the Woosters
• Joy in the Morning
• The Mating Season
• Much Obliged, Jeeves