List of ice based villains and fire based heroes. I'm sure there are more out there.
Ice based Villains:
Blizard [Dark Nemesis]
Blue Snowman (Byrna Brilyant)
Captain Cold (Leonard Snart)
Chill [New Rogues]
Chillblaine I-IV [Flash foes]
Coldsnap [Darrel, Masters of Disaster]
Cryonic Man (Philip, Outsiders foe]
Endless Winter (Delores Winters]
Frostbite [Conglomerate, Qwardian]
Glacier [Expediters, Inc]
Glacier [Titans foe]
Ice King [Evil Eight, Dial H villain]
Iceberg Head [Aquaman foe]
Icicle (Joar Mahkent)
Icicle (James Christie)
Icicle (Cameron Mahkent)
Killer Frost (Crystal Frost)
Killer Frost (Louise Lincoln)
Minister Blizzard [Wonder Woman foe]
Mister Freeze (Victor Fries)
Mrs. Freeze (Nora Fries)
New Moon [Moon Dancers]
Snowman (Klaus Kristin)
Split-Man (Gregory Cahill)
Weather Witch [New Rogues]
Weather Wizard (Mark Mardon)
Yuki-Onna, the Snow Woman [Rising Sun/Superman foe]
Others:
Bizarro [Ice Vision]
Replicant [internalized Captain Cold's Ice Gun powers]
Fire based Heroes:
Bonfire (Anne Fletcher)
Boss Bishonen [Big Science Action]
Boss Bosozuko [Big Science Action]
Burnout (Bobby Lane)
Calamity (Olive Silverlock)
Celsius (Arani Desai)
Corona (Kako)
Crazy Jane (Kay Challis)
Etrigan the Demon
Fever (Shyleen Lao)
Fire (Bonilla DaCosta)
Fireball (Sonya Chuikov)
Fireball [Crusaders, Freedom Fighters ally]
Firebrand (Danette Reilly)
Firebrand (Andre Twist)
Firebrand (Janet Fals)
Firehawk (Lorraine Reilly)
Firestorm (Ronnie Raymond and Jason Rusch)
Flamebird (Thara Ak-Var)
H-Dial weilders
Hot Spot (Isaiah Crockett)
Hotshot (William Lefferts)
Inferno (Frank Verrano, Mighty Crusaders) - no longer licensed by DC
Inferno (Sandy Anderson)
Kishana Lewis [JLA ally]
Linda Danvers
Kid Devil (Edward Bloomberg)
Maya (Chandi Gupta)
Pozhar (Mikhail Arkadin)
Pyrogen (Claudio Tielli)
Red Inferno (Seth Aiden)
Red Star (Leonid Kovar)
Rising Sun (Izumi Yasunari)
Salamander (Ginger O'Shea)
Samurai (Toshio Eto)
Scorch (Aubrey Sparks) - sometime ally of J'onn J'onzz
Scorch (Scott Fischer)
Son of Vulcan (Miguel Devante)
Sparky [Crusaders, Freedom Fighters ally]
Sunburst (Takeo Sato)
Sunburst (Takeo's replacement)
Wildfire (Carol Vance Martin)