Agent S is a squirrel agent seen in "Cheer Up Candace". He then appeared in "Phineas and Ferb Christmas Vacation!" and in Phineas and Ferb the Movie: Across the 2nd Dimension.
Mindless animal mode
In mindless animal mode, he is pretty much like other squirrels.
- According to his secret file, his bushy tail is the envy of other rodents. He takes vacation time during nut-storing season, and is comfortable living in rural and urban settings.
- "Cheer Up Candace" (First appearance)
- "Phineas and Ferb Christmas Vacation!"
- "Phineas and Ferb the Movie: Across the 2nd Dimension"
- "Where's Perry? (Part One)" (silhouette)
- "Just Our Luck" (Cameo)
- "Phineas and Ferb Save Summer"
- "O.W.C.A. Files"
- Where's My Perry? (Secret file)