If the first alien were to have some sort of wingy looking thing and a tail added, it would make a great Zenethian Soulslayer proxy! The green thing with headwrap would be a good basis for a Golem of Darkness.
For non-WZ comments, Mr. Walky-Fish is cool, as are the Spartan-esque warriors. The goule in the last pic is solid as well. Overall, great work!