'Real Genius' Star Gabriel Jarret Gets Restraining Order Against Houseguest

Gabriel Jarret, who co-starred with Val Kilmer in "Real Genius," claims his ex-GF went nuts on him ... refusing to leave his home, and accusing him of child molestation, rape and more ... TMZ has learned.

Gabriel filed for and got a restraining order Monday against Jennifer Marie Alfano ... and in the docs he says she called him a few weeks ago, crying about being thrown out of a hotel and losing all of her possessions, so he let her use his Santa Monica apartment for a few hours to clean up.

But, Gabriel, who played Mitch in the '80s cult classic film, says she refused to get out and screamed outrageous accusations -- calling him a pedophile, drug dealer and rapist -- so loudly his neighbors overheard.

In the docs, obtained by TMZ, he says Jennifer chased his friend around the block for 20 minutes before cops arrived and convinced her to leave. Only problem is she allegedly left with a laptop, social security cards, birth certificate and jewelry -- none of which belonged to her.

He's worried about getting evicted because his neighbors and landlord are fed up. Although he called her an ex-GF in the docs ... Gabriel tells us he never had a romantic relationship with Jennifer.