Mathis later appeared in American Psycho (2000), a film adaptation of Bret Easton Ellis's 1991 novel of the same name.
She starred in Attraction (2000), and in The Simian Line (2001).
“They were always a fun band to watch, and tonight, they played well. You can stand and you can talk,'” Forrest writes in the book.
It was great fun until I felt a hand tap my shoulder and turned to see River. “Bob, I don’t feel so good,” Forrest recalls Phoenix telling him. “I still have guilt that I dismissed his worries so casually.” Shortly thereafter, a commotion erupted in the club, and Forrest rushed to the door to find Phoenix’s girlfriend, “American Psycho” actress Samantha Mathis, screaming as her boyfriend convulsed on the sidewalk.
She costarred in the television series Aaron's Way and Knightwatch from 1988 to 1989.
Her first starring role in a feature film was that of Nora in Pump Up the Volume (1990), opposite Christian Slater, whom she briefly dated at the time.
In his new memoir “Running With Monsters” (Crown Archetype, available now), “Celebrity Rehab” star Bob Forrest — who chronicles his days as a drug addict and musician on the Hollywood scene in the book — recalls the night of Phoenix’s death, writing that Phoenix felt he was suffering from an overdose in the moments before his collapse.
She was with Phoenix on October 31, 1993, the night he died at Cedars-Sinai Hospital of a drug overdose after collapsing outside West Hollywood's Viper Room.
She then appeared in The American President (1995), playing the assistant to the President of the United States.
Mathis appeared in the television movies Extreme Close-up, 83 Hours 'til Dawn, and To My Daughter in 1990.
Mathis and Slater had voice roles in the animated film Fern Gully: The Last Rainforest (1992).
Also read: Hollywood’s Notable Deaths of 2013 In the book, Forrest recalls being at Johnny Depp‘s nightclub The Viper Room, one of Forrest’s haunts and the scene of Phoenix’s collapse.