First mentioned in Chapter 25, the "Baby" is a short, elderly man, and an infamous Neo-Nazi leader. He worships Johan as an ideal Aryan leader who would be able to become the next Hitler to lead Germany into prominence. He also works for the four individuals who would gladly welcome Johan as a political leader. To this end, he hoped to use Nina as bait to coerce Johan, but also as a precautionary measure to protect him (and the other group members) from Johan.

Spoiler

This fails as Johan kills one of the first of four members in the organization.
In the second half of the series he grows depressed and confides in a prostitute, he is later killed by this prostitute in a scheme engineered by Johann.

The characteristics of the "Baby" is heavily influenced by the character "The Man from Another Place" from Twin Peaks. His first appearance, in Chapter 26/Episode 15, is also nearly identical, appearing to Nina Fortner from behind a red curtain (akin to the Black Lodge's waiting room) while dancing to the tune "Be My Baby". (Source: Wikipedia)