Madeline Bassett (later Lady Sidcup) is a character in P. G. Wodehouse's Jeeves series of books. She is one of the fiancees to whom Bertie Wooster ineptly finds himself practically engaged. She is fond of declaring that the Milky Way is "God's daisy chain," and that, in a slightly contradictory way as Bertie silently notes, a "wee bit star" is born each time a fairy sheds a tear. Wooster describes her (in Right Ho, Jeeves) in the following terms: "She was a pretty enough girl in a droopy, blonde, saucer-eyed way, but not the sort of breath-taker that takes the breath."

The daughter of Sir Watkyn Basset of Totleigh Towers, Madeline is a friend of Bertie’s cousin Angela (the daughter of his Aunt Dahlia Travers). They meet on a trip to Cannes (in Right Ho, Jeeves) during which she notices that he looks at her with long, dumb, searching looks. What for Bertie is mere tongue-tied wolly-headedness Madeline mistakes for pining love, and when he pleads in the third person the cause of Gussie Fink-Nottle, who adores Madeline from afar, Madeline of course mistakes this for a proposal.

Bertie escapes this scrape only to re-encounter Madeline in Code of the Woosters and Stiff Upper Lip, Jeeves, though she eventually marries Roderick Spode, 8th Earl of Sidcup, thus becoming Lady Sidcup.