I purchased a house on land contract --- The warranty deed is in one persons name and he quick claimed the house to his girlfriend. She is the one who I have the land contract with. Is it legal? And can he take the house back?

OK, once he QUIT CLAIM (not guick claim) he no longer owns the property, the girlfriend owns it. The new deed ends the old one.
It does not matter what type of deed, warranty , special, quit, they are all legal deeds.

As long as you have a contract with the person listed on the most recent deed.

And if he has a lien on the house (selling it to his girlfriend) he could foreclose of course. But if she sells the house to anyone else, they are required to honor and accept any contract, or lease or rental on the home.

(Thanks for correcting my grammar) --- my original question was this
I purchased a house on land contract --- The warranty deed is in one persons name and he quit claimed the house to his girlfriend. She is the one who I have the land contract with. Is it legal? And can he take the house back?

What I did not include was ---

Raymond - purchased the house and financed it through a bank. There is still a balance owed to the bank. He then Quit Claimed it to Diane (girlfriend). She then signed a land contract with me --- Does this change you anser?