He is a Decapodian, a crustacean-like species of alien, who works as the staff doctor for Planet Express, despite his woeful understanding of human physiology and allusions to his questionable credentials.
His character parodies the supposed wealth and automatic respect of modern doctors—for example, his incompetence at human medicine makes him extremely poor despite his profession, and he is implied to be frequently homeless when not at work.
Zoidberg is voiced by Billy West, who performs the character with a Yiddish-inflected accent inspired by actors George Jessel and Lou Jacobi.
[3] During the first season, jokes surrounding Zoidberg usually focused on his poor understanding of human anatomy and his resulting incompetence as a doctor, and the fact that all of his co-workers hate him.
As the series progressed, writers gradually introduced the themes that Zoidberg is also poor, homeless, friendless, smelly, undignified, and repulsive[5]—comically opposite the idea that a doctor stereotypically occupies a respectable, wealthy, and romantically desirable role.
Zoidberg also generally attempts to make himself look refined, successful, and important in front of others, though this illusion is quickly dashed when pointed out.
[7] Other intimations to his dubious medical training include the episode "Teenage Mutant Leela's Hurdles", in which he comments, "I'm no robot doctor, but this machine guy could really use a lozenge.
"[8] Although he is shown to be incompetent at treating humans, the episode "The Tip of the Zoidberg" shows he is a competent doctor for alien species, such as the Yeti.
The crew are often disgusted by his foul habits, such as squirting ink or eating from trash cans, though he is mostly oblivious to their true feelings about him, having referred to Hermes Conrad and Bender as friends.
When frightened or fleeing from danger or trouble, Zoidberg makes a high-pitched whooping sound, similar to Curly Howard of The Three Stooges, or squirts ink at his attacker.
"A Taste of Freedom" and Futurama: Bender's Game indicate that Zoidberg harbored a childhood dream of working in show business as a comedian or song-and-dance man, but that his parents pushed him to become a doctor.
Zoidberg's race, the Decapodians—from the sandy, beach-like planet Decapod 10—are crustaceans, generally lobster-like in appearance, with lobster-like claws, mouth tentacles, a hard exoskeleton, a fleshy, boneless interior, a fin that appears atop their heads during mating season or extreme anger, an ink pouch, two stomachs (one saltwater and one freshwater), four hearts, gonopores, and a complex system of internal organs, "most of which are either redundant or unnecessary."
He is an honorary member of the Harlem Globetrotters, and a talented hand-to-claw combatant; he severs Fry's arm in an honor-duel ("Claw-Plach") and eventually fights and defeats the dangerous robot Clamps.
Dr. Zoidberg finally finds happiness in the episode "Stench and Stenchibility", when he meets and starts dating a flower merchant named Marianne, who suffers from anosmia.
Zoidberg had largely corrected his medical blind spot concerning human anatomy, as demonstrated by Marianne's transplant and his earlier complete re-assembling of Hermes' body from cast-off parts.