Career
She is perhaps best known for her portrayal of Beth in the 1995 horror film Halloween: The Curse of Michael Myers. Acting
O'Brien has appeared in films such as Gas, Food Lodging, Halloween: The Curse of Michael Myers, Being John Malkovich, Diamonds, Ticker, The Mod Squad, and Some Girl. Her television credits include Buffy the Vampire Slayer, Charmed, The Nanny, Once and Again and Courting Alex.
Modelling
O'Brien is featured on the cover of the Alice in Chains album Dirt.