Semi-convenient list of avatars by type:
Fighters:
Erol Otus: D&D B/X Basic Set Cover
Larry Elmore: D&D BECMI 'Blue Box' Expert Rules, BECMI 'Green Box' Companion Rules, BECMI 'Black Box' Master Rules, AC10 Bestiary of Dragons and Giants (2 images), Caramon (DL novel cover), Tika (DL novel cover), Kitiara (DL calendar), Caramon (DL5 Dragons of Mystery), Tika (DL5 Dragons of Mystery)
Jeff Easley: D&D BECMI 'Red Box' Basic Rules (4 images), AD&D 2nd edition Player's Handbook
Keith Parkinson: FR Forgotten Realms Campaign Set
Clyde Caldwell: I11 Needle, REF3 The Book of Lairs, GAZ2 The Emirates of Ylaruam, GAZ14 The Atruaghin Clans, DL calendar, Dragon Magazine #76, Dragon Magazine #172, FRC1 Ruins of Adventure, FRC2 Curse of the Azure Bonds, FRE3 Waterdeep, FR Forgotten Realms Adventures
Jim Holloway: D&D BECMI 'Red Box' Basic Rules
Gerald Brom: Dark Sun Campaign Setting Box Set (a psionicist in the novels), DSE1 Dragon's Crown, DSR1 Slave Tribes, CGR2 Complete Book of Gladiators (specifically a gladiator rather than fighter)
Miscellaneous: Jeff Dee (D&D B/X Basic Rules), Timothy Truman (X5 Temple of Death), Stephen Fabian (GAZ1 The Grand Duchy of Karameikos), Fred Fields (Champions of Mystara)
Paladins/Knights:
Larry Elmore: Sturm (DL5 Dragons of Mystery)
Keith Parkinson: Sturm (DL calendar)
Miscellaneous: Jeff Butler (DL11 Dragons of Glory), Valerie Valusek (FOR6 The Seven Sisters), Glen Orbik (PHBR12 The Complete Paladin's Handbook)
Rangers:
Larry Elmore: Riverwind (DL5 Dragons of Mystery)
Keith Parkinson: PHBR11 Complete Ranger's Handbook
Clyde Caldwell: I11 Needle, PHBR11 The Complete Ranger's Handbook (2 images)
Miscellaneous: Julie Bell (PHBR11 The Complete Ranger's Handbook)
Barbarians:
Larry Elmore: CN2 Conan the Mercenary
Clyde Caldwell: CN1 Conan the Buccaneer, RS1 Red Sonja Unconquered (4 images)
Mages:
Erol Otus: D&D B/X Basic Set Cover
Larry Elmore: D&D BECMI 'Red Box' Basic Rules, Raistlin (DL novel cover), Raistlin (DL5 Dragons of Mystery), FR Book of Lairs
Jeff Easley: FR4 The Magister
Clyde Caldwell: GAZ3 The Principalities of Glantri, AC4 The Book of Marvellous Magic, WG5 Mordenkainen's Fantastic Adventure, WG11 Puppets, FR Campaign Setting 2nd edition, FR6 Dreams of the Red Wizards, FRE3 Waterdeep, RA2 Ship of Horror
Miscellaneous: Timothy Truman (B7 Rahasia), Stephen Fabian (GAZ3 The Principalities of Glantri), Terry Dykstra (FA2 Nightmare Keep), Terry Dykstra (D&D Rules Compendium), Fred Fields (FR novel cover)
Clerics:
Larry Elmore: D&D BECMI 'Red Box' Basic Rules (3 images), BECMI 'Blue Box' Expert Rules, BECMI 'Green Box' Companion Rules, Elistan (DL5 Dragons of Mystery), Goldmoon (DL5 Dragons of Mystery), PHBR3 Complete Cleric's Handbook
Jeff Easley: DL2 Dragons of Flame
Keith Parkinson: DL3 Dragons of Hope
Clyde Caldwell: Goldmoon (DL calendar)
Jim Holloway: B4 The Lost City
Miscellaneous: Doug Chaffee (AD&D 2nd edition Dungeon Master's Guide)
Thieves:
Larry Elmore: D&D BECMI 'Red Box' Basic Rules, BECMI 'Blue Box' Expert Rules, BECMI 'Green Box' Companion Rules (3 images)
Jeff Easley: ALQ1 Golden Voyages
Keith Parkinson: Fafhrd (Lankhmar City of Adventure), The Gray Mouser (Lankhmar City of Adventure)
Clyde Caldwell: CM9 Legacy of Blood, GAZ9 The Minrothad Guilds
Jim Holloway: Spelljammer Campaign Setting Box Set
Miscellaneous: Jack Pennington (DLE3 Dragon Keep), Fred Fields (LNA1 Thieves of Lankhmar), Fred Fields (LNR1 Wonders of Lankhmar), Glen Orbik (PHBR7 The Complete Bard's Handbook), Glen Orbik (GA3 Tales of Enchantment)
Oriental Adventures classes:
Jeff Easley: Samurai (Oriental Adventures hardcover)
Clyde Caldwell: Samurai (Endless Quest #23), Ninja (OA2 Night of the Seven Swords)
Jim Holloway: Yakuza (OA4 Blood of the Ninja), Ninja/Kunoichi (Dragon Magazine #151)
Miscellaneous: Fred Fields (FROA1 Ninja Wars)
Dwarves:
Larry Elmore: D&D BECMI 'Red Box' Basic Rules, Flint Fireforge (DL5 Dragons of Mystery), PHBR6 Complete Book of Dwarves
Keith Parkinson: PHBR6 Complete Book of Dwarves
Clyde Caldwell: REF3 The Book of Lairs, Flint Fireforge (DL novel cover)
Jim Holloway: B4 The Lost City, Dragon Magazine #117
Gerald Brom: FR11 Dwarves Deep
Mul/Half-Dwarf:
Gerald Brom: DS Dragon Kings
Elves:
Larry Elmore: D&D BECMI 'Red Box' Basic Rules, BECMI 'Green Box' Companion Rules, Gilthanas (DL5 Dragons of Mystery), Laurana (DL5 Dragons of Mystery), Gilthanas (DL7 Dragons of Light), Silvara (DL7 Dragons of Light)
Jeff Easley: Paco and Lathan (XS1 Lathan's Gold)
Clyde Caldwell: Laurana (DL14 Dragons of Triumph), GAZ5 The Elves of Alfheim, novel cover
Gerald Brom: DLS4 Wild Elves, Dragon Magazine #197, DSS3 Elves of Athas
Miscellaneous: Stephen Fabian (GAZ3 The Principalities of Glantri), Tony Szczudlo (Polyhedron Magazine #107)
Half-Elves:
Larry Elmore: Tanis (DL5 Dragons of Mystery Cover), Tanis (DL5 Dragons of Mystery)
Drow:
Erol Otus: D3 Vault of the Drow
Keith Parkinson: GDQ1-7 Queen of the Spiders
Clyde Caldwell: GAZ5 The Elves of Alfheim (intended to be a shadow elf)
Halflings:
Clyde Caldwell: I11 Needle
Gnomes:
Jim Holloway: AC11 The Book of Wondrous Inventions
Kender:
Larry Elmore: Tasslehoff (DL novel cover), Tasslehoff (DL5 Dragons of Mystery)
Tiefling:
Tony DiTerlizzi: PS Monstrous Compendium Appendix I
Dragons:
Erol Otus: D&D B/X Basic Set Cover
Larry Elmore: D&D BECMI 'Red Box' Basic Rules, BECMI 'Blue Box' Expert Rules, BECMI 'Green Box' Companion Rules, AC10 Bestiary of Dragons and Giants, DL6 Dragons of Ice
Jeff Easley: AD&D 2nd edition Dungeon Master's Guide, DL2 Dragons of Flame
Keith Parkinson: CM3 Sabre River, DL calendar, Dungeon Magazine #1
Clyde Caldwell: DL1 Dragons of Despair, DL10 Dragons of Dreams, DL calendar
Miscellaneous: Denis Beauvais (Dragon Magazine #122)
Monsters:
David A. Trampier (all from Monster Manual): Banshee (Groaning Spirit), Basilisk, Coatl, Baalzebub (Devil), Dispater (Devil), Displacer Beast, Dragon Turtle, Efreet, Fire Giant, Frost Giant, Goblin, Gorgon, Griffin, Intellect Devourer, Lich, Lizardman, Minotaur, Pseudo-Dragon, Rakhasa, Remorhaz, Giant Spider, Vampire, Wererat (Lyncanthrope)
Erol Otus: Behir (S4 Lost Caverns of Tsojcanth), Decapus (B3 Palace of the Silver Princess), Giant Frog (I1 Dwellers of the Forbidden City), Myconid (A4 In the Dungeons of the Slave Lords), Otyugh (S3 Expedition to the Barrier Peaks), Roper (Rogues Gallery), Sahuagin (Monster Cards 1), Shrieker (S3 Expedition to the Barrier Peaks), Giant Snake (Monster Cards 1), Treant (Monster Cards 1), Umber Hulk (Monster Cards 2)
Larry Elmore: Ogre (D&D BECMI 'Red Box' Basic Rules), Chimera (BECMI 'Blue Box' Expert Rules), Beholder (BECMI 'Green Box' Companion Rules), Orc (FR5 The Savage Frontier), Gnoll (FR8 Cities of Mystery)
Jeff Easley: Pegasus (AD&D Monster Manual new cover), Ghoul (D&D BECMI 'Red Box' Basic Rules), Rust Monster (BECMI 'Red Box' Basic Rules), Lich (BECMI 'Black Box' Master Rules), Demogorgon (BECMI 'Gold Box' Immortals Rules), Type V Demon Marilith (BECMI 'Gold Box' Immortals Rules), Gargoyle (B7 Rahasia), Bone Golem (B7 Rahasia), Pegataur (M2 Vengeance of Alphaks), Unicorn (DL1 Dragons of Despair), Githyanki (OP1 Tales of the Outer Planes), Skeleton (FR Ruins of Undermountain), Kuo-Toa (Night Below: An Underdark Campaign)
Keith Parkinson: Lich (I3-5 Desert of Desolation), Lich (CA2 Swords of Deceit), Hellhound (X11 Saga of the Shadow Lord), Lich (X13 Crown of Ancient Glory), Sivak Draconian (DL calendar), Bozak Draconian (DL calendar), Aurak Draconian (DL calendar), Lord Soth (DL calendar), Skeletal Warrior (DL calendar)
Clyde Caldwell: Lizardman (B9 Castle Caldwell and Beyond), Harpy (PHBR11 The Complete Ranger's Handbook), Mummy (RA3 Touch of Death), Vampire (I6 Ravenloft), Vampire (I10 Ravenloft II: The House on Gryphon Hill), Wyvern (Dragon Magazine #72), Takhisis (DL calendar), Lord Soth (DL calendar)
Jim Holloway: Bugbear (AD&D 2nd edition Monstrous Compendium 1), Gelatinous Cube (MC2), Hobgoblin (MC1), Mind Flayer (MC1), Thri-Kreen (AD&D Monster Manual II), Yuan-Ti (Monster Manual II), Zargon (B4 The Lost City), Giff (Spelljammer Campaign Setting Box Set)
Gerald Brom: Minotaur (DLR2 Taladas the Minotaurs), Unknown Creature (Dark Sun Campaign Setting Box Set), Unknown Creature (DSE1 Dragon's Crown)
Tony DiTerlizzi: Gibbering Mouther (AD&D 2nd edition Monstrous Manual), Owlbear (Monstrous Manual), Stirge (Monstrous Manual), Tarrasque (Monstrous Manual), Aasimar (PS MC Appendix II), Archon (PS Planes of Law), Cat Lord female (PS MC Appendix I), Cranium Rats (PS Campaign Setting Box Set), Demon/Tanar'ri Succubus (PS MC Appendix I), Demon/Tanar'ri Type VI Balor (PS MC Appendix I), Devil/Baatezu Erinyes (PS MC Appendix I), Eladrin Ghaele (PS MC Appendix II), Modron Monodrone (PS Planes of Law), Modron Quadrone (PS Campaign Setting Box Set)
Miscellaneous:
- David Sutherland: Chimera (AD&D Monster Manual), Cockatrice (MM), Air Elemental (MM), Earth Elemental (MM), Fire Elemental (MM), Water Elemental (MM), Kobold (MM), Troglodyte (MM)
- Russ Nicholson: Githyanki (Fiend Folio)
- Timothy Truman: Water Weird (B7 Rahasia), Goblin (MSOLO1 Blizzard Pass), Minotaur (MSOLO2 Maze of the Riddling Minotaur), Lizardman (N1 Against the Cult of the Reptile God)
- Helen Bedford: Hutaaka (AC9 Creature Catalogue)
- David Simons: Kraken (DMR2 Creature Catalog), Vampire (DMR2 Creature Catalog)
- Doug Chaffee: Orc (AD&D 2nd edition Player's Handbook), Troll (PHBR1 The Complete Fighter's Handbook)
- Terry Dykstra: Beholder (D&D Rules Compendium)
- Todd Lockwood: Orcus (Dragon Magazine 42)
- Dennis Kauth: Faerie Dragon (Dragon Magazine #100)
- Paul Jacquays: Mind Flayer (Dungeon Magazine #24)
- Bruce Eagle: Medusa (DMGR6 Complete Book of Villains)
- Unknown: Flumph (AD&D 2nd edition Monstrous Compendium 2nd Annual), Centaur (AD&D 2nd edition Monstrous Manual), Hydra (Monstrous Manual), Manticore (Monstrous Manual), Mermaid (Monstrous Manual)
- Dana Knutson: Sea Serpent (RL Castles Forlorn Box Set)
- Robh Ruppel: Rakshasa (RM3 Web of Illusion), Zombie (RQ1 Night of the Walking Dead)
- Glen Michael Angus: Aboleth (Night Below: An Underdark Campaign)
Other:
David A. Trampier: Adventurer (Monster Manual), Idol (Players Handbook)
Erol Otus: Cthulhu (Deities & Demigods), Hastur (Deities & Demigods), Primordial One (Deities & Demigods), Yog-Sothoth (Deities & Demigods), Thoth (Legends & Lore), Great Green Devil (S1 Tomb of Horrors)
Jeff Easley: Dungeon Master (D&D BECMI 'Red Box' Basic Rules), Hand/Eye of Vecna (WGA4 Vecna Lives)
Keith Parkinson: H2 The Mines of Bloodstone, DL4 Dragons of Desolation
Tony DiTerlizzi (all from PS Campaign Setting Box Set): The Lady of Pain, The Bleak Cabal, Doomguard, Dustmen, Fated, Harmonium, Mercykillers, Sensates, Transcendent Order a.k.a. Ciphers, Xaositects (also a Githzerai)
Miscellaneous:
- Jim Roslof: Thor versus Jormungandr (Deities & Demigods / Legends & Lore)
- John Blumen: Woman Riding Giant Lizard (Dragon Magazine #47)
- Tom Baxa: The Spelljammer (Legend of the Spelljammer Box Set)
- Erik Olson: Nautiloid (SJR3 Spelljammer Dungeon Master's Screen)
- Fred Fields: Woman (D&D Hollow World Box Set)
- Stephen Fabian: Vistani (Ravenloft Campaign Setting Box Set)
- Dana Knutson: Planescape Logo (Planescape Campaign Setting Box Set)