Susanna Kaysen is an American author.

Kaysen was born and raised in Cambridge, Massachusetts. Kaysen attended high school at the Commonwealth School in Boston and the Cambridge School before being sent to McLean Hospital in 1967 to undergo psychiatric treatment for depression. It was there she was diagnosed with borderline personality disorder. She was released after eighteen months. She later drew on this experience for her 1993 memoir Girl, Interrupted, which was made into a film in 1999, her role being played by Winona Ryder.

She is the daughter of the economist Carl Kaysen, a professor at MIT and former advisor to President John F. Kennedy. Her mother, deceased, was sister of architect Richard Neutra. Kaysen also has one sister and has been divorced at least once. She lived for a time in the Faroe Islands, upon which experience her novel Far Afield is based.