Scarleteen

So I've read on here that if you have unprotected anal sex and he doesn't cum there is a slight pregnancy risk, if he just put the head in my butt and pulled right out is there still a risk? Also how is there a risk if he doesn't cum?

Anal sex still presents a risk even without ejaculation because of pre-ejaculate (pre-cum): the fluid that's released when a person with a penis gets an erection. It doesn't contain sperm all by itself, but as I mentioned in another thread of yours, it can pick up leftover sperm on its way out of the urethra, which might still be able to help create a pregnancy. With anal sex, if there is enough pre-ejaculate, it can drip down from the anus to the vagina, hence the risk (although it's a pretty low risk; the far bigger concern with anal sex is the risk of infection).

Have you ever heard of anyone actually getting pregnant that way?

Thinking about "possible" scenarios is not very productive. As Karyn mentioned, the risk would be low but there is still a risk. If someone wants to prevent pregnancy by all means their best bet is to use a birth control method. It could be hormonal or a barrier but at least one of them.