Those are guardians of the forest. Run past all of them and in the stone arch, talk to the cat that should be sitting up above you. You can join the covenant and become one of them, thus making them friendly. The translucent ones don't reappear if you happen to kill them, though.
I would join that covenant regardless, because one of the NPCs there will venture to the bottom of Blighttown near the bonfire and the Valley of the Drakes entrance. He sells a bunch of the rarer items and weapons.
Also, if you happen to attack him, a ninja will come to defend him. Kill the ninja and you get a ring that lets you do backflips and stuff instead of just roll around.