Gruenwald is a pirate captain in the West Indies.
During the events of Black Sails: Season 1 Episode 4 IV. played by Greg Parves
Rackham tries to have Gruenwald sell Captain Charles Vane's hauls as if it were his own, but Gruenwald is worried that if Eleanor Guthrie find out then he would also be blacklisted. Gruenwald then asks Rackham why he stays with Vane.