Stephanie Lynne Niznik (May 20, 1967 – June 23, 2019) was an American film, television, and theatre actress, most famous for her role as Nina Feeney on Everwood.

Niznik grew up in Brewer, Maine, and was co-valedictorian of the Class of 1986 at John Bapst Memorial High School where she was an exchange student to Paris, participated in genetic research at Jackson Laboratory, and was a National Merit Scholar.^[1][2] She intended to become a geneticist and gained early acceptance to Harvard University before entering and graduating magna cum laude from Duke University where she changed her goals, majoring in theater and Russian.^[3][1] She then graduated from the California Institute of the Arts.^[4] Besides Everwood, Niznik's television roles include guest roles on Dr. Quinn, Medicine Woman, Profiler, Sliders, JAG, Frasier, Epoch, Star Trek: Enterprise, Traveler, and Diagnosis: Murder, in addition to being a series regular on the mid-1990s action drama Vanishing Son and the 2007 drama Life Is Wild. She also appeared in the films Star Trek: Insurrection and Exit to Eden. After retiring from acting in 2009, Niznik focused on volunteerism.^[1]

She died in Encino, California on June 23, 2019, at the age of 52,^[3][5] from chronic liver disease associated with alcoholism.^[6]