Joseph Gruen

Joseph Gruen was a member of Wardenclyffe Section, a secret research organization of the United States Federal Government that was dedicated to the investigation of several mysterious infectious organisms. More specifically, he acted as the supervisor of Goodluck.

Altered timeline
After the Lord of Dust was defeated by the castaways, Goodluck was told off by Gruen with his "mistake" regarding the next wormhole occurring as a result of the Ground Zeroes Incident. He then warned Goodluck that the heads of the Section most likely won't be happy with Goodluck's subordination and will "come down hard" on him for it.

Behind the scenes
Goodluck is a major character who appears in the spin-off game Metal Gear Survive, acting as the main character's handler.