Mera, wife of Aquaman - to the point where she was briefly inducted into the Red Lantern Corps during the Blackest Night crossover. In the post-Rebirth continuity, she took on the entire Justice League while in Unstoppable Rage mode and gave them a serious run for their money.
Barbara "Babs" Gordon, in the current continuity (originally, she was a Brainy Brunette; Batgirl's red hair was a wig attached to the cowl).
Erin Mc Killen, Irish mobster who scarred Harvey Dent in the New 52. Would also qualify as an Evil Redhead.
Wally West, the first Kid Flash and third Flash, is very impulsive, and his terrible temper is a consistent flaw of him even after the Character Development. This contrasts him with his slow-thinking mentor Barry Allen, the second Flash.
Wally: Superman has Kryptonite, Martian Manhunter has fire...I have a temper.
The Green Lantern Guy Gardner. Described by Nash as "Loud, and angry, and obnoxious, and ginger!"
Callie Evans of Robin may be a natural brunette but she dyes her hair a reddish orange and is outgoing, outspoken and passionate.
Starfire is fierce in combat, and not only is she a redhead, but also her hairstyle makes it look like flames, which causes a literal version of the trope. Depending on the Artist, she sometimes has literal Flaming Hair (it starts out normal and ends in flames).
In the Golden Age of Comics Etta Candy was a redheaded tomboy who loved fights, boys and candy and led a group of gals to fight Nazis at every opportunity.
From Wonder Woman (1987) on Artemis of the Bana-Mighdall qualifies as a redheaded Amazon who often serves as a more violent, less compassionate but far more impassioned foil to Diana.
Hunter's Hellcats: The redheaded Heller is famous for her fiery temper. Her need for vengeance drove her to join the WACs in an attempt to find the man who killed her father, despite the fact that he could be anywhere in the US theatre of operation, and her explosive temper landed her in the guardhouse for assaulting a superior officer, which is where Ben Hunter recruited her for the Hellcats.
Angela is a redheaded Asgardian warrior and as fiery and boisterous as most other Asgardians.
Natasha Romanov, the Black Widow. Started out with black hair and was only "revealed" as actually a redhead in her ASM #86 makeover. Did not become appreciably fierier after the change.
Jean Grey and Rachel Summers, who not only fit the personality trope, but also happen to manifest their powers in the form of giant birds made of fire. However, Jean often subverts the trope, especially in her pre-Phoenix days, when she was one of the most level-headed Marvel superheroines with a personality very reminiscent of the Fantastic Four's team mommy Sue Storm Richards. Rachel on the other hand has always been fiery, before during and after her own Phoenix days.
Rahne Sinclair of The New Mutants (Excalibur, X-Force, X-Factor, New X-Men...) is at once shy, passionate, religious, conflicted, and a redhead. Her fiery personality is hidden under piety most of the time.
Irish beauty Theresa Rourke Cassidy (X-Force, X-Factor). You don't want her screaming at you.