Hydroweasel

Hydroweasels (also hydro-weasel) are so despised that their name has become a synonym for treachery. Beyond this, little is known, although it seems reasonable to think they inhabit or are otherwise involved with water. This may or may not imply an origin on a planet other than Cybertron.

Fiction

The Transformers cartoon

When Nergill, who was supposedly allied with the Decepticons at the time, was going to blast both Grimlock and Megatron as he couldn't get a clear shot at the Dinobot, Starscream labelled him a traitorous hydroweasel. Atlantis, Arise!

Beast Wars: Uprising

Bisk was known to fight hydro-weasels and other creatures lurking in Cybertron's lower levels. Not All Megatrons