Deep One

The Deep Ones are horrible aquatic humanoids. While ocean-dwelling, they're amphibious enough to mate with humans. The resulting crossbreeds are humans who gradually develop what's known as the "Innsmouth Look" in the story they're from: bulging eyes, shrunken ears, narrow heads, flat noses, and generally going a bit green around the gills they also grow, until they transform into Deep Ones and leave the land behind.

The player can recruit Deep Ones as Minions: they start as human or humanlike beings, who are suited to Infiltration, and become shambling fishmonsters, who are not. They were also in a Kickstarter update that covered extending Procedural Generation to the seas:

The Deep Ones were an obvious choice given their literary origin. In a given Scenario the player may see a Deep One Colony in a shore area, but you didn't have much of a chance to bring about the Innsmouth Look of infamy. Now you can! By expending some Ancient Power in a slightly corrupted port village you can enact "Idols of the Deep" which will grow stronger in the POI over time. If the POI is attacked and taken over the modifier is lost, and it is also lost by certain Religious actions - if, however, it remains until the game begins it will manifest in one of two ways.

1) The POI remained a Village - A Deep One Colony will exist with strength dependent on how many ages the modifier lasted. A Deep One culture will supplant the native culture and a very unusual Cult will be present. Danger to heroes is greatly increased in this POI.

2) The POI upgraded to a City - As above but a Cathedral instead of a Cult, drastically increasing control over the City and the influence of the Deep Ones on land. The Deep One bloodline runs through most of the notables of the town and any heroes that spawn from it.