Max is an Old English Sheepdog and Eric's pet. Unlike all the other animals in the film, Max is minimally anthropomorphic and does not speak in the human language.

During Eric's birthday celebration, Max catches Ariel's scent and tracks her down, licking her on the cheek in an apparent show of affection. When the ship catches fire, the sailors escape safely, but Max is left behind. Seeing this, Eric dives out of his lifeboat and climbs back on board, grabbing Max and tossing him to safety. Later, when Eric is brought to shore safely by Ariel, Max smells out his master and rushes out to greet him. Max is also able to smell Ariel who is hidden off-shore behind rocks, but Eric does not understand his barking.

After Ariel has made her deal with Ursula and is brought to shore as a human, Max leads Eric to her, recognizing her as the same person, though Eric cannot. Eventually, Ursula herself appears in the guise of a human girl named Vanessa to distract Eric from kissing Ariel before the third day is up, but Max is the only character in the human world who can fully see Vanessa for who she really is and is seen growling furiously at her, and during her and Eric's wedding, she kicks him directly in the face. When Scuttle and the sea animals try to stop the wedding, Max assists and gets his revenge by biting her in the butt, giving Scuttle the leverage to break the conch shell containing Ariel's voice. At Eric and Ariel's wedding, Max gives affection licks on their faces.

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