The Spider-Slayers: Part 1 is the twenty first episode of the fourth season of Ultimate Spider-Man.
Spider-Man must team with the former traitor, Scarlet Spider, to stop Doc Ock from reawakening a secret program designed to create evil duplicates of Spider-Man.
- In the beginning of the episode, Peter mentions Loki having swapped bodies with him to backstab the Avengers in The Avenging Spider-Man Part 1.
- This episode marks the return of Scarlet Spider.
- This marks the first animated appearance of Mary Jane as Spider-Woman.
Ultimate Spider-Man Vs. The Sinister Six Peter Parker Meets Spider-Man Official Disney XD UK
| Season 1:
|| Great Power | Great Responsibility | Doomed! | Venom | Flight of the Iron Spider | Why I Hate Gym | Exclusive | Back In Black | Field Trip | Freaky | Venomous | Me Time | Strange | Awesome | For Your Eye Only | Beetle Mania | Snow Day | Damage | Home Sick Hulk | Run Pig Run | I Am Spider-Man | The Iron Octopus | Not a Toy | The Attack of the Beetle | Revealed | The Rise of the Goblin
| Season 2:
|| The Lizard | Electro | The Rhino | Kraven the Hunter | Hawkeye | The Sinister Six | Spidah-Man! | Carnage | House Arrest | The Man-Wolf | Swarm | Itsy Bitsy Spider-Man | Journey of the Iron Fist | The Incredible Spider-Hulk | Stan By Me | Ultimate Deadpool | Venom Bomb | Guardians of the Galaxy | The Parent Trap | Game Over | Blade | The Howling Commandos | Second Chance Hero | Sandman Returns | Return of the Sinister Six | Ultimate
| Season 3:
|| The Avenging Spider-Man (Part 1, Part 2) | Agent Venom | Cloak and Dagger | The Next Iron Spider | The Vulture | The Savage Spider-Man | New Warriors | The Spider-Verse (Part 1, Part 2, Part 3, Part 4) | The Return of the Guardians of the Galaxy | S.H.I.E.L.D. Academy | The Rampaging Rhino | Ant-Man | Burrito Run | Inhumanity | Attack of the Synthezoids | The Revenge of Arnim Zola | Halloween Night at the Museum | Nightmare on Christmas | Contest of Champions (Part 1, Part 2, Part 3, Part 4)
| Season 4:
|| Hydra Attacks (Part 1, Part 2) | Miles From Home | Iron Vulture | Lizards | Double Agent Venom | Beached | Anti-Venom | Force of Nature | The New Sinister Six (Part 1, Part 2) | Agent Web | The Symbiote Saga (Part 1, Part 2, Part 3) | Return to the Spider-Verse (Part 1, Part 2, Part 3, Part 4) | Strange Little Halloween | The Spider Slayers (Part 1, Part 2, Part 3) | The Moon Knight Before Christmas | Graduation Day (Part 1, Part 2)