Kaine Parker/Scarlet Spider (Marvel Comics) can burn distinctive scars into people and object with his Mark of Kaine...
...as he demonstrates on Carnage.
Anti-Venom's (Marvel Comics) very skin is caustic to the Venom symbiote.
Agent Anti-Venom's (Marvel Comics) suit is caustic to symbiotes...
...and Poisons, as they are predators that thrive off of symbiotic biomass.
Sanj (One Piece) using his Diable Jambe technique to inflict devastating burns onto his opponents.
Monkey D. Luffy's (One Piece) Gum Gum/Gomu Gomu no Redhawk can cause vicious burns onto his opponents.
Roy Mustang (Fullmetal Alchemist: Brotherhood) can his mastery over Flame Alchemy to induce severe burns onto his opponents.
Gabimaru (Hell’s Paradise: Jigokuraku)
Sirin/Herrscher of the Void (Honkai Impact 3rd) using Inflammation.
When Lavagirl (The Adventures of Sharkboy and Lavagirl) is angry or becomes enraged, her hair ignites into bright pink flames. However, when she's calm or asleep, her powers 'cool off' until she emits almost no heat.