Actress Stephanie Niznik, best known for playing Treat Williams’ next-door neighbor in the WB drama Everwood, has died. A report in Variety said her death came unexpectedly June 23 in Encino, Calif.

The Maine-born actress, who was a National Merit Scholar and a valedictorian at her high school, once dreamed of becoming a geneticist but chose an acting career instead. She appeared in movies like Exit to Eden and Star Trek: Insurrection but she found her biggest success on the small screen. Niznik showed up in series as diverse as Murder, She Wrote, Dr. Quinn, Medicine Woman, and JAG, before snagging a series regular role in Diagnosis: Murder from 1998-2000. Two years later, she was cast in Greg Berlanti’s drama Everwood as Nina — a role she played for four seasons.