From issue #4 of the first Hercules miniseries, in 1982, by Bob Layton (story, pencils, and inks).

This story took place in an alternate future, so it wasn't necessarily canon, but Ron Marz and Ron Lim used this depiction of Galactus without his helmet in 1991's Silver Surfer #51.

Good find! I wonder who remembered it in '91 when Marz and Lim planned that sequence.

In the UK, this miniseries was used as the back-up strip for Transformers.

He has a very Kirby look to him; like one of the Eternals or something.