Silent Hill 3

When the worm is inside a hole, hold down R1 (attack stance, default settings) to determine which hole it's coming out of next. Back away from that hole a bit to avoid getting knocked down. When the worm appears wait for it to "open" its "face" (the lids absorb all damage, so don't bother shooting as long as they're closed). Once the lids are open shoot the worm's face. If you're out of bullets equip a melee weapon (I'd recommend the steel pipe for its decent range), run closer to the face and whack it a few times (though avoid getting bitten). Rinse and repeat.

Hold R1 to get your weapon ready and wait for him to come out of one of the holes. When he does, wait for him to open his mouth and attack him. You may want to use the handgun, but if you have no ammo, just wait for it to come at you and hit it with a melee weapon before it reaches you. Once you know how to beat it, it is a relatively easy boss.
- LemonPenguin