Before Hydro Hunter became a meta human affected by Eobord Thawne, he was a bank robber wanted by Detective Joe West and Eddie Thawne. Hydro Hunter has the ability to transform various limbs in to water, using them to attempt to drown The Flash. However, he also seemed to be partly made of water, dissolving when he came into contact with a lot of it. Due to his power, he was nicknamed that by Cisco Ramon.
Hydro Hunter appeared in Gotham City which was why Eobord Thawne sent the Flash over to locate and capture him. The Flash teamed up with Bruce Wayne to take him on and Bruce was able to defeat Hydro Hunter by purchasing a pharmaceutical from a drug store to use it in order to make Hydro Hunter freeze himself before turning him over to the GCPD.
He appeared in the Flash: Season Zero comics in the issue Smoak Signals Part One