Captain America himself can qualify, though it's worth pointing out that he's associated with red as much as he is with white and blue for obvious reasons.
And both their Distaff Counterparts, Mary Marvel and Ms. Marvel (Carol Danvers) respectively, have worn red Gendered Outfit versions of the males' costumes at times. (At other times, Mary Marvel wears a white version instead, while Ms. Marvel is better known for a black costume and since taking the "Captain" title herself has switched to a mainly-blue one.)
Crimson Avenger
Daredevil's original costume was mostly yellow, but his classic look is all-red. He is also a redhead.
Deadman is a ghost with chalk-white skin in a red outfit.
Doctor Strange wears black with red accents since his 2011 redesign. His former look (and the costume most closely associated with him) included a distinctive and showy red cloak.
Impulse (Bart Allen) has always been linked with the color red, even in Young Justice where all four of the core members of the team wore the color he was the one who got to be associated with it.
Iron Man's standard color scheme is red and gold, although some of his "specialized" suits buck the trend.
Jean Grey is a variation. She is a redhead and usually a hero but when she goes Dark Phoenix her costume becomes red. That
During the "All-New Marvel NOW!" relaunch of 2013-2014, the Fantastic Four traded in their signature blue uniforms for red and black ones.
New Gods: The three primary heroic characters wear red. Orion wears a red suit, Mr Miracle's outfit is red, yellow, and green, and Big Barda's cape is red.
During the New 52, Nightwing replaced his traditional blue trim with red trim. While still a hero, it also reflected him going through a Darker and Edgier phase, and he later switched back to blue.
Though their costumes change constantly, the Robins are often drawn with predominantly red costumes (Tim Drake being the most notable one, especially after Identity Crisis (2004)when his father died, as he'd been previously associated with green). And of course, there's Tim Drake as Red Robin.
Scarlet Witch (as an Avenger, anyway) wears a flowing red mantle, a red headdress, and a red Leotard of Power, which she often pairs with a pink bodysuit for femininity.
Although she already wore that costume when she still was one of the Brotherhood of Evil Mutants led by Magneto, who by preference dresses in red and purple.
And her teammate/lover The Vision, who has artificial red skin.
Shang-Chi tends to wear outfits that are either predominantly red or have some red in them.
Teen Titans: The original team consisted of Robin, Wonder Girl, Kid Flash and Aqualad. All of them wore outfits which featured red prominently. They were later joined by Speedy who also wore red.
On that note, Thor's red cape is an iconic part of his costume and a good indicator of his heroic status.
Vampirella is a heroic vampire that wears a red bikini, also doubling as a Lady in Red. Her alternate outfits also tend to be red. There is also the Sisterhood of the Scarlet Legion, an order of warrior nuns who fight evil. As their name implies, their uniforms are red.
