We have headhunter skins, so why not have Alien inspired champ skins

Zyra - Could be like the alien queen. Her turrets would match her skin design of course, and her ranged turrets would spit green acid at enemy champs.

Kog'Maw - this one is easy enough, and he already kind of fits the design

Cho'Gath - same as above

Kha'Zix - already looks a little bit like a xenomorph

Elise - Her humanoid form would be sort of, but not too similar to Zyra's. Her spiders would be modeled after her spider form and when they explode they would excrete green acid

Shyvana - Her humanoid form would once again be a little similar to Zyra's. Her dragon form could be inspired from the actual queen xenomorph in alien vs. predator.

Note

I am not a very talented artist, but I will do my best to come up with splash art as soon as possible for each champion I have mentioned.