Treasure Gremlin - Steals 100 coin from you, you can get the coin back if you kill them but if there are 10 successful thieveries then a rich treasure gremlin spawns in the area carrying 1000c plus anything they steal. Chance to drop gems for selling in the coin minter or displaying in shop stands.
Munchkin Gremlin - Leaves gifts in the area it spawns containing different drops from the planet, can be hugged for a small heal, and if killed drops a broken heart for crafting a sacrificial alter.
Cookie Gremlin - Will sell you 100 cookies for 500c, any money the cookie gremlins make they spend on buying cookies from shop stands, cookies restore health and hunger, but remove buffs (or not if we want cookies op). If killed just drop 1-5 cookies and some bones and meat.
Chance for all gremlins to drop a gremlin ear, 1000 of which craft a lucky charm which can be held for 10% luck boost.
Any other gremlin ideas?