Guy Stuart Ritchie (born 10 September 1968, Hatfield, Hertfordshire) is an English screenwriter and filmmaker.

Ritchie was born on 10 September 1968, the second of two children born to John Vivian Ritchie and his first wife, the former Amber Parkinson. Ritchie, who is dyslexic, was expelled from Stanbridge Earls School, one of the most prominent institutions specialising in dyslexia in the UK, at the age of 15.. He has stated that drug use was the reason for the expulsion; his father, however, has said that it was because his son was caught "cutting lessons and entertaining a girl in his room."

In addition to his elder sister, Tabitha, a dance instructor, Ritchie has a half-brother, Kevin Bayton, who was born to Amber Parkinson when she was a teenager and given up for adoption.