Appearances:

Giant Man, Iron Man, Incredible Hulk, Wasp, Namor, Watcher, Rick Jones

What If...? #10     August 1978
"Jane Foster had found the Hammer of Thor?"
based on Journey Into Mystery #83

Writer:  Don Glut
Artist:  Rick Hoberg
Inker:  Dave Hunt
Letters: Carol Lay

Appearances: 

Watcher, Stone Men of Saturn, Thordis, Heimdall, Loki, Balder, Volstagg, Hogun, Fandral, Odin, Sif, Radioactive Man, Lava Man, Cobra,  Mister Hyde, Iron Man, Captain America, Giant Man, Mangog, Vizier

What If...? #25      February 1981
"Thor and the Avengers battled the Gods?"
based on Thor #136

Writer:  Peter Gillis
Artist:  Rick Buckler
Inker:  Dave Simmons
Letters: Orz

Appearances: 

Watcher, Odin, Captain America, Hawkeye, Scarlet Witch, Quicksilver, Giant Man, Iron Man, Vizier, Heimdall, Loki, Executioner, Enchantress, Balder, Wasp, Sif, Hogun, Igron, Fandral

What If...? #39      June 1983
"Thor battled Conan the Barbarian?"
based on no specific issue

Writer:  Alan Zelenetz
Artist:  Ron Wilson
Inker:  Danny Bulanadi
Letters: Janice Chiang

Appearances: 

Loki, Conan, Crom, Thoth-Amon

What If...? #47        October 1984
"Loki had found the hammer of Thor?"

Writer:  Peter B Gillis
Artist:  Kelley Jones
Inker:  Sam DeLaRosa
Letters: Squid

Appearances: 

Neri, Heimdall, Loki, Odin, Thor, Stone Men of Saturn, Don Blake, Balder, Fandral, Hogun, Volstagg, Hela, Jormungand, Sif

What If...? vol 2 #12     April 1990
"The X-Men had stayed in Asgard?"
based on X-Men Annual #9 and
New Mutants Special Edition #1

Writer:  Jim Valentino
Artist:  Jim Valentino
Inker:  Sam DeLarosa
Letters:  Phil Felix

Appearances:

Rahne, Loki, Mirage, Colossus, Cannonball, Rogue, Sunspot, Karma, Storm, Wolverine, Cypher, Warlock, Shadowcat, Nightcrawler, Magma, Magik, Phoenix, Cyclops, Wolfsbane, Karnilla, Hela, Fandral, Hogun, Volstagg, Thor, Eitri, Balder, Those Who Sit Above In Shadow

What If...? vol 2 #38                                  June 1992
"Thor was a thrall of Seth?"
based on Thor #396

Writer:  Roy Thomas & RJM Lofficier
Artist:  Marshall Rogers & MC Wyman
Inker:  Sam Delarosa & Rod Ramos
Letters: Janice Chiang

Appearances: 

Watcher, Time Keepers, Odin, Fandral, Hogun, Sif, Grog, Seth, Loki, Karnilla, Izanagi, Yu-Huang, Osiris, Vishnu, Buluku, Zeus, Quetzalcoatl, Mephisto, Igron, Irondroid, Dr Doom, Wolverine, Immortus

What If...? vol 2 #66                           October 1994
"Rogue possessed the power of Thor?"
based on Avengers Annual #10

Writer:  Simon Furman
Artist:  John Byrne
Inker:  Bambos
Letters:   Janice Chiang

Appearances: 

Destiny, Avalanche, Pyro, Rogue, Spider-Woman, Vision, Hawkeye, Wonder Man, Scarlet Witch, Beast, Jocasta, Thing, Mr Fantastic, Invisible Woman, Odin, Sif, Fandral, Volstagg, Hogun, Balder, Blob, Mystique, Loki, Human Torch

What If...? vol 2 #107                              April 1998
"Thor ruled Asgard?"
based on Thor #468 (sort of)

Writer:  Tom DeFalco
Artist:  Ron Frenz
Inker:  Bill Sienkiewicz
Letters: Chris Eliopoulos

Appearances: 

Heimdall, Volstagg, Sif, Hogun, Vizier, Fandral, Balder, Thunderstrike, Bloodaxe, Odin, Mephisto, Loki, Black Knight, Crystal, Giant Man, quicksilver, Captain America, Mangog, Balder, Destroyer

What If...? vol 2 #108   May 1998
"The Avengers battle the Carnage Cosmic?"
based on Amazing Spider-Man

Writer:  Tom DeFalco
Artist:  Sergio Cariello
Inker:  Keith Champagne
Letters:  Chris Eliopoulos

Appearances:

Spider-Man, Carnage Cosmic, Thor, Captain America, Vision, Iron Man, Firestar, Justice, Jarvis, Carnage Symbiote, Silver Surfer

What If...? vol 2 #114                         November 1998
"The Marvel Heroes never returned from the Secret Wars"?
based on Marvel Super Heroes Secret Wars #1-12

Writer:  Jay Faerber
Artist:  Gregg Schigiel
Inker:  Jose Marzan Jr
Letters: Chris Eliopoulos

Appearances: 

Balder*, CJ, Sarah, Thor, Rogue, She-Hulk, Iron Man, Wolverine, Storm, Spider-Man, Captain America, Molecule Man, Volcana, Human Torch, Hawkeye, Absorbing Man, Wrecker, Wasp, Dr Doom, Kendall, Trudy, Malefactor, Tucker, Carol, Hulk, Watcher, Sentinels

What If...Thor was the herald of Galactus?        2005

Writer:  Robert Kirkman
Artist: Michael Avon Oeming
Colorist: Val Staples
Letters: Dave Lanphear

Appearances:  Hector, Galactus, Sif, Fandral, Hogun, Volstagg, Loki, Munin, Odin, Balder, Heimdall