Captain Herman Zimmerman (or H. Zimmerman) was a Starfleet officer during the 24th century.
In 2364, he was the commander of the USS Nightwing. (TNG: "Conspiracy", okudagram)
In 2368, he was listed as being part of the Engineering Group on the second dedication plaque of the USS Enterprise-D. (TNG: "Silicon Avatar", dedication plaque)
In 2370, he was the commander of the USS Yorktown on a Deep Space 9 arrival roster. (DS9: "Whispers", okudagram)
This was the only reference where he was referenced as "H. Zimmerman".
He was listed as being the part of the Science Ops team on the dedication plaques of Defiant-class starships USS Defiant (2370), USS Valiant (2372), and USS Sao Paulo (2375). (DS9: "The Die is Cast", dedication plaque; DS9: "Valiant", USS Valiant dedication plaque; DS9: "The Dogs of War", dedication plaque)
In 2372, he was listed as belong to the Spaceframe Development team on the dedication plaque of the USS Enterprise-E. (Star Trek: First Contact, dedication plaque)
This character was only mentioned in writing.