"She has been the weakest one, the strongest one, the sanest one, the craziest one. She has been the nurturer and the dependent. They want all this from her and more."
-Apocalypse on Jean Grey
Hellcat, Medusa, Mystique, and of course the other members of the extended Jean brood (Rachel, Madelyne, Hope, Fongji). Crystal and Wanda may qualify as honorable mentions, their hair is probably closer to what people actually have in real life than that bright and bold red which I'm pretty sure can't actually occur naturally despite its prevalence in comics. As for the guys, the incomparable Cain Marko, who for my money is leaps and bounds more interesting than Colossus and should be reinstated as the One True Juggernaut any day now.
Fun fact - Genghis Khan, of all people, also had red hair and green eyes.
Naturally red hair definitely has more of a copper look to it than the more romanticized fire or shiny apple red depicted in books. I think this is about as red as hair will get as far as genetics will allow.
Dustin Nguyen though Marvel would have to poach him from DC. He drew this gorgeous ode to comic book redheads.
Jean, MJ, Firestar, Siryn, Mystique and Medusa representing Marvel. Fairchild, Batwoman, Batgirl, Poison Ivy and Starfire round up the pile.
Fonji doesn't qualify for the book on account of not being a real character.
Hear me X-men! No longer am I the woman you once knew! I am fire and life incarnate! Now and forever...
I AM PHOENIX!
When Jean eventually does come back for real, Marvel needs to re-establish her glamorous image, and ditch the frumpy, dowdy ginger Sue Storm schtick she had going for a while there. Of course, this would have to be done in a tasteful, elegant, and understated manner, not the sort of tacky and oversexualized dreck that passes for glamour these days (think Dazzler, Psylocke, or Emma at their worst excesses). True beauty and grace can be found somewhere in between butt floss and mom jeans, and that's where Jean should live.
It's not just about clothes though, the way she carries herself has to match as well. This is all on the artist of course, but it really can make a huge difference in how she's perceived. Just look at Hope, yeah her face might be identical to Jean's but the way she poses and presents herself is so full of testosterone that I'm half expecting her to sprout a massive ginger beard at any minute now.