On September 1, 1987, Gruenwald became Marvel's executive editor, with a particular remit as the keeper of continuity.
Gruenwald was famous for a perfect recollection of even the most trivial details.

In the pages of Thor, writer Walt Simonson created the Time Variance Authority, a cosmic bureaucracy that regulates the Marvel Multiverse.
Simonson paid homage to Gruenwald by having the TVA's staff all be clones of Gruenwald; no one could keep track of everything but him.

Gruenwald (or "Gru" or "Grueny" as he was often referred to) was a recurring character with Tom DeFalco in the single-panel comic The Bull's Eye that ran in Marvel comics in the late 1980s–early 1990s, created by Rick Parker and Barry Dutter.
These strips, which ran on the Bullpen Bulletins page during the majority of DeFalco's run as editor-in-chief, featured Gruenwald depicted as a caricature and foil for DeFalco's antics.
On September 1, 1987, Gruenwald became Marvel's executive editor, with a particular remit as the keeper of continuity. Gruenwald was famous for a perfect recollection of even the most trivial details.
In the pages of Thor, writer Walt Simonson created the Time Variance Authority, a cosmic bureaucracy that regulates the Marvel Multiverse. Simonson paid homage to Gruenwald by having the TVA's staff all be clones of Gruenwald; no one could keep track of everything but him.
Gruenwald (or "Gru" or "Grueny" as he was often referred to) was a recurring character with Tom DeFalco in the single-panel comic The Bull's Eye that ran in Marvel comics in the late 1980s–early 1990s, created by Rick Parker and Barry Dutter. These strips, which ran on the Bullpen Bulletins page during the majority of DeFalco's run as editor-in-chief, featured Gruenwald depicted as a caricature and foil for DeFalco's antics.
Mark Gruenwald