The Spider-Slayers: Part 1 is the twenty first episode of the fourth season of Ultimate Spider-Man.
- Avengers (mentioned)
- Nova/Sam Alexander (mentioned)
- Arnim Zola (mentioned)
- Curt Connors (mentioned)
- Loki (mentioned)
- Drake Bell as Spider-Man and Kaine
- Tara Strong as Mary Jane Watson/Spider-Woman
- Scott Porter as Scarlet Spider
- Tom Kenny as Doctor Octopus
- In the beggining 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.