I think there might be at least one snake in every game. In KQ1, there's a snake. You can't do anything with it except get some comments from the game, but it's there. In KQ2, there's Pegasus who has been turned into a snake. In KQ3, talking snakes can be found in the desert. In KQ4, a cobra guards the fruit. We all know about KQ5's POISONOUS snake (thanks Cedric, we would never have noticed that without you!). Actually, KQ5 has more than one snake, since Mordack turns into both a snake and a dragon. In KQ6 you can see the genie disguised as a snake when you give your ring to Sing Sing. KQ7 has a dragon. We GRACEfully learn in "Gabriel Knight" that myths about dragons actually come from snakes, so that counts. I never finished KQ8 so I don't know if that has any snakes.

Spiders are prominently featured too. There's one in KQ3, KQ5, KQ6, and 2 in KQ7. For those that don't know about the one in KQ5, it can appear in the witch's forest, but I think only if you've made the game unwinnable (If you don't have the honeycomb or if you wasted all your emeralds).

Only in the remake though, and is really only part of the scenery.

Well, there's still a dragon in the original KQ1