Lisa Robin Kelly, who played Topher Grace's older sister on That '70s Show, has died at the age of 43, ET has confirmed.
"Unfortunately Lisa Robin Kelly passed away last evening," her agent tells us in a statement. "Lisa had voluntarily checked herself into a treatment facility early this week where she was battling the addiction problems that have plagued her these past few years. I spoke to her on Monday and she was hopeful and confident, looking forward to putting this part of her life behind her. Last night she lost the battle. Cause of death has not been issued yet and no death certificate has been issued either."
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Kelly had publicly struggled with her addiction; she was arrested four times in the last three years for a variety of charges from DUI to assault.
Kelly's '70s Show co-stars were devastated by the news. In a statement to ET, Tanya Roberts wrote:
"I was in shock when I heard the news of Lisa's passing. I really thought she was getting herself together. What an incredible waste. Lisa was so young and so talented. She was always so great on 'That ‘70s Show.' She never missed a line. Not to mention what an incredibly sweet and funny person she was. My heart goes out to her family and friends."
Danny Masterson also commented on the unsettling news on Twitter.