Christine Dolce -- better known as ForBiddeN on MySpace during its super early days, who amassed over 2.1 million friends -- died from liver failure ... TMZ has learned.

Christine was arguably MySpace's biggest star in its heyday -- behind Tom, of course -- and built an enormous following after posting tons of pics with her in racy outfits. Rock star David Navarro and Nine Inch Nails were just some of her many followers.

Christine's family tells TMZ ... she had been hospitalized since December after battling with alcohol-related issues. Christine -- who famously feuded with Tila Tequila's crew and built a brand that included a clothing line -- had tried getting help but to no avail.

She died at the hospital surrounded by family. Her funeral was last week.