| Name | CR | Type | Environment |
| Taniniver | 18 | dragon | any land or underground |
| Taniwha | 6 | magical beast (aquatic) | warm rivers |
| Tanuki | 4 | monstrous humanoid (shapechanger) | temperate forests or urban |
| Taotieh | 11 | construct | any |
| Tarantula Tree | 19 | plant | temperate or tropical forests |
| Targotha | 15 | aberration | any swamps (tar seeps) |
| Tatterlorn | 7 | undead | any urban |
| Tattoo Guardian | 3 | construct | any |
| Tatzlwyrm | 2 | dragon | any forests |
| Tauhoti | 1/6 | animal | temperate forests or hills |
| Taxidermic Grizzly Bear | 3 | construct | any |
| Tear of Nuruu'gal | 6 | ooze (fire) | any land |
| Tekenu | 6 | undead | warm ruins |
| Telgrodradt | 6 | aberration | underground |
| Tendriculos | 6 | plant | temperate or warm forests |
| Tenebrous Blight | 6 | plant | any underground |
| Tenebrous Worm | 8 | outsider (extraplanar) | any land (Plane of Shadow) |
| Tengu | 1/2 | humanoid (tengu) | temperate mountains or urban |
| Tenome | 4 | monstrous humanoid | any urban |
| Tentamort | 4 | aberration | any marshes or underground |
| Termite Swarm | 6 | vermin (swarm) | warm forests, plains, or underground |
| Terra-Cotta Soldier | 6 | construct | any |
| Tetrolimulus | 11 | magical beast (aquatic) | temperate coasts |
| Thassilonian Sentinel, Bronze Sentinel | 3 | construct | any |
| Thassilonian Sentinel, Iron Sentinel | 5 | construct | any |
| Thassilonian Sentinel, Ivory Sentinel | 7 | construct | any |
| Thassilonian Sentinel, Marble Sentinel | 4 | construct | any |
| Thawn | 2 | humanoid (giant) | temperate hills and plains |
| Thessalhydra | 18 | aberration | temperate swamps |
| Thin Man | 4 | fey | warm plains (Nuat) |
| Thoqqua | 2 | outsider (earth, elemental, extraplanar, fire) | any land (Plane of Fire) |
| Thorgothrel | 8 | ooze | any |
| Thought Eater | 2 | aberration (extraplanar) | any (Ethereal Plane) |
| Thrasfyr | 17 | magical beast (fire) | any |
| Thremindyr | 9 | outsider (air, cold, native) | cold hills or mountains |
| Thriae, Thriae Constructor | 14 | monstrous humanoid | any |
| Thriae, Thriae Dancer | 6 | monstrous humanoid | any |
| Thriae, Thriae Queen | 18 | monstrous humanoid | any |
| Thriae, Thriae Seer | 11 | monstrous humanoid | any |
| Thriae, Thriae Soldier | 4 | monstrous humanoid | any |
| Thrushmoor Angler | 8 | magical beast (aquatic) | temperate forests, swamps, and water |
| Thunderbird | 11 | magical beast | any hills or mountains |
| Thylacine | 1/2 | animal | warm hills |
| Thylacine, Brush Thylacine | 2 | animal | temperate forest |
| Tiberolith | 10 | construct | any coastlines or water |
| Tick, Giant Tick | 1 | vermin | temperate forests |
| Tick, Tick Swarm | 9 | vermin (swarm) | temperate forests |
| Tidewretch | 6 | undead | any coastlines |
| Tiefling | 1/2 | outsider (native) | any land |
| Tiger | 4 | animal | any forests |
| Tiger, Dire Tiger (Smilodon) | 8 | animal | any forests, plains, and swamps |
| Tikbalang | 9 | monstrous humanoid | warm jungles or forests |
| Tikoloshe | 3 | undead (aquatic) | warm forests, oceans, or rivers |
| Time Dimensional | 14 | outsider (extraplanar) | any (Dimension of Time) |
| Titan, Elysian | 21 | outsider (chaotic, extraplanar, good) | any land (Elysium) |
| Titan, Hekatonkheires | 24 | outsider (chaotic, evil, extraplanar) | any |
| Titan, Thanatotic | 22 | outsider (chaotic, evil, extraplanar) | any (Abyss) |
| Titanboar | 6 | animal | temperate hills or forests |
| Titanic Whip Spider | 16 | vermin | temperate or warm hills |
| Tiyanak | 6 | undead | any forests |
| Tizheruk | 5 | magical beast | temperate rivers or marshes |
| Toad, Giant Toad | 2 | animal | temperate forests, plains, or swamps |
| Toad, Glacier Toad | 6 | magical beast (cold) | cold hills or glaciers |
| Tobongo (Mwangi Treant) | 12 | plant | warm jungles |
| Tojanida | 5 | outsider (extraplanar, water) | any water (Plane of Water) |
| Tongue of Rebuke | 9 | construct | Dragonfall |
| Tooth Fairy | 1/4 | fey (extraplanar) | any urban or plains |
| Tooth Fairy, Tooth Fairy Monarch | 3 | fey | any urban |
| Tophet | 10 | construct | any |
| Torble | 1/8 | vermin | — |
| Torble, Torble Swarm | 2 | vermin (swarm) | — |
| Tortoise, Giant Tortoise | 1 | animal | warm deserts or islands |
| Tortoise, Immense Tortoise | 8 | animal | warm islands |
| Totenmaske | 7 | undead (shapechanger) | any land or underground |
| Trailgaunt | 3 | undead | any land (wilderness) |
| Treant | 8 | plant | any forest |
| Trench Mist | 10 | aberration (air) | any |
| Trench Mist, Trench Zombie | 6 | undead (augmented human, human)
| — |
| Triaxian | 1/2 | humanoid (Triaxian)
| — |
| Tribal Totem | 6 | construct | any |
| Triton | 2 | outsider (native, water) | any oceans |
| Troggle | 4 | humanoid (giant) | cold hills and mountains |
| Troggle, Troggle Raider | 6 | humanoid (giant) | cold hills and mountains |
| Troglodyte | 1 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Beast-Speaker | 3 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Champion | 7 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Chieftain | 8 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Priest | 3 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Scale-Rider | 6 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Skulker | 2 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Sorcerer | 4 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Tyrant | 10 | humanoid (reptilian) | any underground |
| Troglodyte, Troglodyte Warren Guard | 9 | humanoid (reptilian) | any underground |
| Troll | 5 | humanoid (giant) | cold mountains |
| Troll, Canopy Troll | 3 | humanoid (giant) | temperate or warm forests |
| Troll, Chimney Troll | 2 | humanoid (giant) | any urban |
| Troll, Flood Troll | 2 | humanoid (giant) | temperate swamps or rivers |
| Troll, Ice Troll | 4 | humanoid (cold, giant) | cold mountains or underground |
| Troll, Jotund Troll | 15 | humanoid (giant) | cold hills or mountains |
| Troll, Moss Troll | 3 | humanoid (giant, shapechanger) | cold or temperate forests |
| Troll, Mountain Troll | 14 | humanoid (giant) | cold mountains |
| Troll, Rock Troll | 6 | humanoid (earth, giant) | any underground |
| Troll, Sewer Troll | 2 | humanoid (giant) | any underground |
| Troll, Troll Acolyte | 6 | humanoid (giant) | cold mountains |
| Troll, Troll Berserker | 9 | humanoid (giant) | cold mountains |
| Troll, Troll Brute | 7 | humanoid (giant) | cold mountains |
| Troll, Troll Elder Matron | 10 | humanoid (giant) | cold mountains |
| Troll, Troll Fury | 8 | humanoid (giant) | cold mountains |
| Troll, Troll Monarch | 15 | humanoid (giant) | cold mountains |
| Troll, Troll Render | 10 | humanoid (giant) | cold mountains |
| Troll, Troll Ripper | 8 | humanoid (giant) | cold mountains |
| Troll, Troll Warden | 6 | humanoid (giant) | cold mountains |
| Trollhound | 3 | magical beast | cold mountains |
| Trompe l'Oeil | 6 | construct | any urban |
| Troop, Barrier Breaker Troop | 7 | undead (troop) | any land |
| Troop, Cultist Troop | 11 | humanoid (elf, troop) | any underground |
| Troop, Goblin Troop | 5 | humanoid (goblinoid, troop) | temperate
forests or plains (usually
coastal regions) |
| Troop, Outlaw Troop | 7 | humanoid (human, troop) | any land |
| Troop, Sodden Drauger Troop | 9 | undead (troop) | any coastal |
| Troops, Dottari Troop | 7 | humanoid (human, troop) | — |
| Troops, Glorious Reclamation | 14 | humanoid (human, troop) | any |
| Troops, Hobgoblin Phalanx Troop | 10 | humanoid (goblinoid, troop) | any land |
| Troops, Hound Archon Troop | 16 | outsider (archon, extraplanar, good, lawful, troop) | any (Heaven) |
| Troops, Inquisitor Troop | 9 | humanoid (human, troop) | — |
| Troops, Ironfang Magehunter Troop | 14 | humanoid (goblinoid, troop) | any |
| Troops, Ironfang Siege Alchemist Troop | 16 | humanoid (goblinoid, troop) | any |
| Troops, Ironfang Yzobu Rider Troop | 18 | humanoid (goblinoid, troop) | any |
| Troops, Morlock Swarmer Troop | 7 | monstrous humanoid (troop) | any underground |
| Troops, Warmaze Disciples Troop | 11 | monstrous humanoid (troop) | any mountains or underground |
| Trox | 2 | monstrous humanoid | tropical deserts |
| Tsaalgrend | 2 | plant | any underground |
| Tsukumogami, Boroboroton | 5 | outsider (kami, native) | any |
| Tsukumogami, Kasa-obake | 4 | outsider (kami, native) | any |
| Tsukumogami, Koto-furunishi | 2 | outsider (kami, native) | any |
| Tullimonstrum | 1 | animal (aquatic) | any oceans |
| Tulpa | 6 | outsider (augmented humanoid, human) | any |
| Tunche | 17 | fey | warm forests |
| Tupilaq | 7 | construct | any |
| Turtle | 1/6 | animal | temperate or tropical forests, oceans, and rivers |
| Turtle, Giant Snapping Turtle | 9 | animal | temperate or warm water or shore |
| Turtle, Snapping Turtle | 1/3 | animal | temperate or warm water or shore |
| Turul | 19 | outsider (extraplanar) | any (Positive Energy Plane) |
| Tuyewera | 4 | undead | any |
| Twigjack | 3 | fey | temperate forests |
| Typhilipede | 2 | outsider (evil, extraplanar, lawful) | any underground (Hell) |
| Tzitzimitl | 19 | undead | any |