You might find this list of comic book members of the US Navy to be of interest though it looks incomplete and I can't vouch for its accuracy.
Also, DC's Skyrocket was a Naval Aviator.
There seem to be quite a few Naval villians, though.
The anti-Captain America was a Navy SEAL.
scifi.stackexchange.com/users/4025/Mark Beadles
Alpha One : A metahuman from a non-aligned DC Universe continuum, who gained his powers from a radiation accident while he was a sailor exposed to radioactive water.
He later gains superhuman abilities which make him appear to be as powerful as Post-Crisis Superman, replete with flight, super-strength, near-invulnerability, super-senses and energy projection from his eyes.
However he is sorely lacking in the excellent moral sense we associate with Superman.
He appears in a 12 issue maxi series called The Mighty.
Cover for The Mighty Issue #4 THE MIGHTY was a maxi-series that ran from ’09 to ’10 and its plot upped the stakes significantly in the usual relationship between a superhero and his human allies.
It’s about a regular cop in Section Omega, a special police unit that aides the operations of their world’s
only superhero, Alpha One.
However, when that hero starts becoming corrupt with his own power, the cop’s faced with the impossible challenge of trying to take down a godlike immortal when he, himself, has no superpowers.
Paramount is considering optioning this character into a movie .
scifi.stackexchange.com/users/2765/Thaddeus Howze
First one that comes to mind would be DC comics's Firebrand Wikipedia profile You can find more info about this character here
If it's for a gift, i would recommend the first isues of the All-Star Squadron were this character is wounded during the Pearl Harbor attack
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When the members of the Justice Society decided they want to fight WWII in the military, almost all the male members joined the Army.
Except one.
Johnny Thunder joined the Navy.
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As far as I remember in the series: Superman: Red Son, Hal Jordan is part of the US Navy as commander , under the presidency of Lex Luthor, as a intent for fight back Superman.
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I have been looking all over the internet to answer this question and I can't find anything. There's plenty of Air Force superheroes, but I can't find any Navy.  This is the start of a gift idea for a friend of mine who is more into comics than I am. He recently joined the Navy and I thought it would be neat to get him some HeroClix characters that served in the Navy.
Are there any comic book heroes (DC or Marvel preferably) that served in the US Navy (not marines)?
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<comics><marvel><dc>
scifi.stackexchange.com/questions/27897
scifi.stackexchange.com/users/11283/DaMavster
Johnny Thunder joined the Navy.  Also consider Alpha One: A metahuman from a non-aligned DC Universe continuum, who gained his powers from a  radiation accident  while he was a sailor exposed to radioactive water.  It is also worth mentioning Superman: Red Son, in which Hal Jordan is a US Navy Commander. Hal Jordan and Johnny Thunder are part of the Navy. Moreover, Alpha One also discloses a hero who serves in the Navy.
Hal Jordan is part of the Navy. Alpha One also discloses a hero who serves in the Navy. Johnny Thunder is also in the Navy.