A penguin and the leader of the group. First person: I (authoritative). He acts as the tactical commander, giving missions code names and providing precise instructions to his team. He has a penchant for black humor and possesses the personality of a stereotypical military officer. Described by Kowalski as having a "personality disorder," he is highly suspicious and prone to wild, paranoid delusions. He tends to look down on non-bird animals and occasionally displays old-fashioned attitudes. However, he is a highly capable leader and combatant who goes to great lengths to fulfill his subordinates' wishes, earning him deep loyalty from his team and even occasional affection from enemies. He sometimes gives his team members "slaps of love." His mottos are democracy and his home-grown proverb: "There's only one way to do a job: the right way. My way."

The brains of the Penguins, responsible for situation reports and devising strategies. First person: I (polite/intellectual). He carries a clipboard and pen, analyzing situations instantly. He owns an abacus, scales, and a scratch-and-sniff animal encyclopedia. While confident in his intelligence, he is poor at reading human writing; consequently, his plans and reports consist almost entirely of drawings. If his brain or body takes damage, he may regress to childish speech. He usually speaks calmly, but his voice cracks when he gets excited. He is also surprisingly prone to tears.

The most violent and physical member of the group. He has a mohawk-like tuft of feathers on the back of his head and a scar on the left side of his beak. He rarely speaks in coherent sentences, communicating instead through grunts, roars, single words, and onomatopoeia, though the other penguins and animals seem to understand him perfectly. First person: Rico. His catchphrases include "Kaboom!" and "Fish!" He has a bottomless stomach where he stores weapons and tools, regurgitating everything from musical instruments to machinery and howitzers upon request.

The youngest member and the most level-headed penguin in the group. First person: I (polite/soft). He has a very gentle, kind personality and relies on his cuteness as a primary asset. He speaks with a polite, slightly deferential tone.

A self-proclaimed king of the ring-tailed lemurs. He is self-centered and a troublemaker.

A Goodman's mouse lemur and Julien's servant. He is childlike and free-spirited. He loves Julien, but Julien finds him annoying.

An aging aye-aye who serves as Julien's caretaker. He is generally loyal.

The middle-aged female zookeeper. She has a poor work ethic.