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- Major/Colonel Glenn Talbot in Tales to Astonish #61
- Talon in Guradians of the Galaxy # 18
- Tarantula in The Amazing Spider-Man #134
- Taskmaster in Avengers #195
- Techno (as Fixer) in Strange Tales #141
- Terrax in Fantastic Four #211
- Terror Inc. in Terror Inc. #1
- Thanos in Iron Man #55
- Thena in Eternals #5
- Thor in Journey into Mystery #83
- Thor Girl in Thor (vol. 2) #22 (as "Thor Girl" in #33)
- Thunderbird in Giant-Size X-Men #1
- Thunderbolts in Incredible Hulk #449
- Thunderstrike (Eric Masterson) in Thor #391
- Thundra in Fantastic Four #129
- Tiger Shark in Sub-Mariner #5
- Tigra in Tigra: Giant-Size Creatures #1 (see the Cat)
- Titania
- I: Davida DeVito in Marvel Two-in-One #54
- II: Mary MacPherran in Marvel Super Heroes Secret Wars #3
- Toad in X-Men #4
- Tombstone in Web of Spider-Man #35
- Transformers in The Transformers #1
- Trevor Fitzroy in X-Men #281
- Triton in Fantastic Four #45
- Turbo in New Warriors #28
- Typhoid Mary in Daredevil #254
- Tyr in Journey into Mystery #85
Read more about this topic: List Of First Appearances In Marvel Comics Publications