Flik

• Adorkable
• Badass Bookworm: Becomes this during his stand against Hopper.
• Character Development: Goes from being the misfit of the colony to the hero of the film.
• Determinator: Wants to gain his colony's approval so darn badly.
• Dogged Nice Guy: For Princess Atta.
• Heroic BSOD: After he gets banished from the colony. He gets better with help from Dot and the circus bugs.
• Intergenerational Friendship: With Dot, mainly because she's the only ant in the colony who admires and looks up to Flik.
• The Millstone: Was this for most of the film until he...
• Took a Level in Badass: Despite being given a No-Holds-Barred Beatdown from Thumper under Hopper's orders, he gives Hopper a Reason You Suck Speech and inspires the rest of the colony to stand up to the grasshoppers.

Atta

• Defrosting Ice Queen: She is rather dismissive towards Flik and his ideas on improving the harvest in the beginning of the film. But warms up to him in the middle.
• Everything's Better with Princesses
• Hartman Hips
• Love Interest
• Tsundere: A rather mild example, it's clear she sees Flik as something of an annoyance at the beginning but doesn't get too extreme about it.

Dot

• The Cutie
• Eleventh Hour Superpower: "Come on, wings. Fly, fly!"
• Intergenerational Friendship: With Flik
• Kid Appeal Character
• Plucky Girl
• Spanner in the Works: She overheard the grasshoppers' plan to squish the queen and flew back to the circus wagon to get Flik and company to return to save the colony.
• Youthful Freckles

Hopper

• Affably Evil: When he's in a good mood.
• Ax Crazy: When he's in a bad mood.
• Big Bad
• Disney Villain Death: A mother bird grabs him and feeds him to her chicks, i.e, he gets EATEN ALIVE.
• Even Bad Men Love Their Mamas: Subject to Alternate Character Interpretation; he says that promising mother on her deathbed not to kill Molt is the only reason he has not done so. This could, however, not really be a matter of loving his mother and instead be more of a matter of simply keeping a promise.
• Freudian Excuse: Averted ruthlessly. Unlike other Pixar villains, Hopper has no known "reason" behind his twisted acts.
• Genius Bruiser: He can easily beat down most anybody else in the film, but he's still hardly dumb. He knows that if all the ants stood up the grasshoppers that since they're far more numerous, the ants would easily push them away.
• I Gave My Word: See Even Bad Men Love Their Mamas.
• Karmic Death
• Kick the Dog: A number of times.
• Killed Off for Real
• Obviously Evil
• The Sociopath
• Why Did It Have to Be Snakes?: Birds.
• Would Hurt a Child

Thumper

• Ax Crazy
• The Brute
• Suddenly Voiced: In the outtakes.
• The Unintelligible

Molt

• Annoying Younger Sibling
• The Ditz
• Punch Clock Villain: When the food's collected and the circus is performing, he happily claps and plays along, rather like a child.
  "The circus, the circus, I love the circus!"

P.T. Flea

• Jerkass
• Let's Get Dangerous: There's no denying that's he's a Jerkass, but he shows his courage by heroically attacking what he thought was a real bird to save everyone.
• Karma Houdini: Despite the fact that he changes his attitude in the end, he never really gets his comeuppance for some of the things he did in the film.
• Unwitting Instigator of Doom: And how!

Heimlich

• Big Eater
• Funny Foreigner

Francis

• Berserk Button: "SO! Being a ladybug automatically makes me a girl! Is that it, fly boy?! Huh?!"
• Dude Looks Like a Lady
• Jerk with a Heart of Gold
• Real Men Wear Pink
• Tertiary Sexual Characteristics: Parodied and subverted. He has long eyelashes, full lips and a beauty mark.

Slim

• Deadpan Snarker
  "Swish swish. Clang clang."
• Grievous Harm with a Body
• You Are A Tree, Charlie Brown

Rosie

• Team Mom
• Woman in Black: Being a black widow spider, though she doesn't carry the usual characteristics.

Dim

• Big Guy
• Gentle Giant
• Man Child

Manny and Gypsy

• Cool Old Guy: Manny
• Cloud Cuckoolander: Gypsy seemed much more interested in her appearance than her husband walking into the walls.
• Interspecies Romance
• Large Ham: Manny.
• The Klutz: Manny.

Tuck and Roll

• Keep It Foreign: They never learn a word of English, except... "You fired!" Word Of God says they're Hungarian.
• The Unintelligible