Jodi Lyn O'Keefe (born October 10, 1978) is an American actress and model, who at age 17 portrayed Cassidy Bridges on Nash Bridges. She is also known for her role on Prison Break as Gretchen Morgan, a.k.a. "Susan B. Anthony".

O'Keefe was born in Cliffwood Beach, New Jersey, the daughter of Noreen, a homemaker, and Jack O'Keefe, a director of labor relations for Merck. She is of Irish, Czech, Austrian, Polish and Swedish ancestry. When she was a child, the youngest of three sisters, she had a bowl haircut and was self-described as a "dork". Her older sister was a model and she decided that she wanted to do the same. She did, and says the modelling job brought her more confidence and more friends. She attended a Catholic school and grew from being the shortest in the class to one of the tallest at 5 feet 8 inches/1.73 metres, the height at which she now stands.

Midway through her junior year high school she left school to star on the soap opera Another World, playing Marguerite “Maggie” Cory. She then got a role on Nash Bridges, playing Cassidy, the daughter of Don Johnson’s title character. She and her mother moved to Hollywood, so Jodi completed her schooling by mail.

She made her big screen debut in 1998 in Halloween H20: 20 Years Later and later starred in such films as The Crow: Salvation, Whatever It Takes and Devil In The Flesh 2. In 1999, she starred in the teen film She's All That (1999) alongside Freddie Prinze Jr and Rachael Leigh Cook. When asked if it was hard to play her character, a high school prima donna, she replied, “Everybody knew a Taylor Vaughan in high school. Working in show business, you meet girls like that every day.”

O'Keefe kept on filming both movies and Nash Bridges until the series ended in 2001. Later films have been Out for Blood where she played a vampire named Layla Simmons and Venice Underground. In 2005, she appeared for three episodes in the first season of Boston Legal.

O'Keefe was also in 3 Doors Down's video "Let Me Go", alongside Jesse Metcalfe of Desperate Housewives. She joined the cast of Prison Break in 2007.

She appeared in episodes of the television series' Charmed, The Evidence, Two and a Half Men, The Big Bang Theory, Dharma & Greg and Tru Calling. In 2009 she appeared in the video game version of Command & Conquer.

On 14 August 2010 Jodi Lyn O'Keefe appeared as Kylie Burch in the Hallmark Original Movie Class. She also appeared in the web series Soul Fire Rising as Lilith Reborn for three episodes.