'Beverly Hills, 90210' & Soap Star David Gail Dead at 58

David Gail -- a soap opera star who acted in several episodes of "Beverly Hills, 90210" has died ... according to his sister.

The actor's sister, Katie Colmenares, shared the tragic news on Instagram Saturday  ... saying she'd "hold you so tight every day in my heart" and she'd miss him "every second of every day forever" -- she did not give a cause of death.

Peter Ferriero, host of a "Beverly Hills, 90210" rewatch podcast confirmed the death as well.

Gail's got numerous credits -- including seven appearances as 'BH: 90210' where he played Shannen Doherty's character's fiancé, Stuart Carson -- but he's best known for his work in the soap opera world.

David appeared on 216 episodes of the "General Hospital" spin-off Port Charles where he played Dr. Joe Scanlon #2, according to IMDb.

A few of Gail's other credits ... "Matlock," "Murder, She Wrote," "The Round Table," "Doogie Howser, M.D.," "Perfect Opposites" and "Growing Pains." He even starred alongside Bradley Cooper in the 2002 rom-com "Bending All The Rules."

Gail was 58.