Brian Austin Green has declared war on a former "90210" co-star who allegedly screwed him out of $200,000 ... and the accused happens to be the mother of his 9-year-old kid.

B.A.G. has filed a lawsuit against Vanessa Marcil-Giovanazzo -- the chick who played Donna's troublemaking cousin on the show -- claiming he let her BORROW a ton of money back when they were dating ... but she NEVER paid him back.

In the lawsuit, filed in L.A. County Superior Court, Green claims he fired off check after check after check to Vanessa ... but insisted "the monies were not gifts" and she promised to pay him back.

Green claims in 2000 -- BEFORE he knocked up Vanessa -- he loaned her up to $50,000 at a time ... and in total, lent her more than $200,000.

In the docs, Green says each time he loaned her money, he and Vanessa agreed that she would pay back the money "promptly" whenever he asked for it. Green says he came calling in November 2011 ... but she refuses to fork over the dough.

Green is demanding all of his cash back -- plus additional unspecified damages.

http://www.tmz.com/2012/01/13/brian-austin-green-lawsuit-vanessa-marcil/

Good luck trying to collect, Brian!!

I would think he could take some less than desirable roles to generate cash rather than sue the mother of his child.

For money she borrowed.

When they were dating.

A long time ago.

Which brings up the lesson no one seems to learn - if it really is "borrowing":

GET IT IN WRITING!!!!!!

Which brings up the lesson no one seems to learn - if it really is "borrowing":

GET IT IN WRITING!!!!!!

:lol: True! His case would never hold up in Judge Judy's courtroom.

Get it in writing - get it notarized!!! It would be hilarious to see this case on Judge Judy. I would TOTALLY watch that. She'd show no mercy. :lol:

http://i42.tinypic.com/2h7j9xf.jpg