Samantha 'Sam' Simpson
The one in the green catsuit (which matches her eyes) with long orange hair, Sam is the leader of the trio. She's smart, kind, pretty, and a bit of a bookworm. She is voiced by Jennifer Hale, who also does Cinderella and fellow TS character Mandy.
The one in the red catsuit with short blonde hair, Clover is a valley girl accented shopaholic who, like your typical teenage girl, is obsessed with fashion, boys, and her looks. Other than that, she really hates Mandy. She's apparently the moving target of the team, seeing how she's usually first affected by whatever the bad guy's planning. She's also the only girl whose father hasn't been seen in the series. She's voiced by Andrea Baker.
Alexandra 'Alex' Vasquez
The dark skinned one in the yellowcatsuit with short black hair, Alex is the athlete of the team, despite her occasional clumsiness. She's also the naive member of the three, since she's younger than Sam and Clover. She's also a terrible driver. She's voiced by Katie Leigh for the first two seasons and by Katie Griffin in the following seasons. Leigh also voiced the Muppet Babies version of Rowlf.
- Sam, Clover and Alex met Kyle in Kyle's Adventures in Totally Spies, a spin off series that's part of The FT Squad Chronicles.
- Sam, Clover, and Alex will meet Dipper and his friends in Dipper & Mabel's Adventures of Totally Spies: The Movie and will guest star in the future Dipper & Mabel's spin-off films.
- Sam is Eddy's girlfriend, Clover is Double D's girlfriend and Alex is Ed's girlfriend.
- Sam, Clover, and Alex will meet Barney the Dinosaur in Barney's Adventures of Totally Spies! The Movie, then they'll appear in several more of Barney's Adventures.
- Sam, Clover, and Alex will join the Monster High crew in upcoming Frankie Stein and Draculaura movies.
- Like Bloom, Sam's hair is colored orange.
- Like Stella (as well as Cornelia and Mina (Sailor Venus), Clover likes shopping, boys and being beautiful.
- Like Layla, Alex loves sports.