Billy Miller — a longtime soap opera star, who starred on some of the most famous shows in the genre — has died, and it sounds like he was battling some demons … TMZ has learned.

A rep for the actor tells us Miller passed away Friday in Austin, TX. An exact cause hasn’t been revealed, but we’re told he was struggling with manic depression at the time of his death. His team suggests he may have taken his own life.

It’s incredibly shocking and sad news for the soap community, as BM was one of the brightest stars in the biz for a good while. The guy had incredible runs on both ‘The Young and The Restless’ as well as a memorable role on ‘General Hospital.’

He starred in over 700 episodes for the former — playing Billy Abbott — and acted in nearly 600 episodes for the latter, playing different characters. In addition to these two iconic shows, he also starred in ‘All My Children’ in the mid-2000s, which kicked off his soap career.

Miller’s work on daytime TV was recognized and praised by his peers — he won Emmys in 2010, 2013 and 2014 for Outstanding Lead and Supporting Actor in a Drama Series for his role on ‘Y&R.’ He was also nominated a handful of other times, including for ‘GH.’

He didn’t just work on soaps, either, BTW — BM acted in a number of other TV series and movies … such as ‘CSI: NY,’ ‘Justified,’ ‘Ringer,’ ‘Castle,’ ‘Ray Donovan,’ ‘Suits,’ ‘Truth Be Told,’ ‘The Rookie,’ ‘NCIS’ and others. He also starred in flicks like ‘American Sniper’ and more.

Miller is survived by his mother, Patricia, and his sister, Megan … as well as other extended family and friends. He was only 43.

RIP