Liquefy (self) – The ability to turn oneself into a liquid. Water mimicry is limited to water.
Zan of the Wonder Twins (DC) can turn into any sort of liquid (Super Friends V1 #7).
Pressure (Malibu) ejects hot liquid from her eyes (1993 SkyBox Ultraverse).
Bloop body consists of liquid and he is part of the Savage Dragon universe.
The Impossibles have Fluidman (Hanna Barbera) as a member who can turn into liquid.