Tilly Bagshawe, born Matilda Emily Mary Bagshawe on 12 June 1973, is a British freelance journalist and author. She is best known for her books written in the style of best-selling American author Sidney Sheldon, such as Sidney Sheldon's Mistress of the Game and Sidney Sheldon's After the Darkness.

Bagshawe was educated at Woldingham School in Surrey and later attended the University of Cambridge. She was a single mother at 17 and took her ten-month-old daughter with her to university. As a journalist, she had a successful career in London, contributing regularly to publications like The Sunday Times, Daily Mail, and Evening Standard before turning to novel writing.

Her first novel, Adored, was published in 2005 and was a hit on both sides of the Atlantic. She subsequently published several other novels, including Showdown (2006), Do Not Disturb (2008), and Flawless (2009).

Bagshawe is married to Robin Nydes, a US businessman, and they have two sons together, Zac and Theo. The family divides their time between Los Angeles and London.