Doctor John Zoidberg is the poor, always hungry, attention craving doctor of the Planet Express company. He's a red crustacean from Decapod 10 - a planet with small, sandy islands surrounded by sea.
Zoidberg is no taller than Fry. He has a round head with large, beady blue eyes. Underneath these eyes is his mouth, which is covered in tentacles. When puzzled, he often rubs his chin with these tentacles. He has four claws, two on his arms, and two on the end of his legs, where humans would have feet. He is much, much stronger than humans are and his claws can cut all but diamond tether. Instead of in his head, his brain is in his rump. Zoidberg changes his shell when it gets old, but the Planet Express budget severely limits his choices.
On the academic side, Zoidberg has three main qualifications: His PhD, which he lost, a mail order degree in Murderology and one in Murderonomy.
Zoidberg's abilities as a doctor are also questionable, but only Cubert has ever brought up this matter. For example, he thinks that the human male genitalia (or 'gonads') are located in the neck region. In fact, he was advised not to become a doctor in the first place. Nevertheless, he was called for duty as a military doctor when Earth's forces invaded Spheron 1 during The Ball Conflict.
He has but one famous acquaintance, his Uncle Harold Zoid who used to star in silent hologram movies. After a glamourous career, Zoid settled down in his not-so-glamourous retirement home until he directed a serious-comedy starring Calculon and Zoidberg.
Every now and then, his specie undergoes a few 'changes' during mating season. The usually calm Zoidberg then transforms into a snarling, drooling pot of male jelly with a large fin protruding from his head. His main love interest during the last love frenzy was another red crustacean named 'Edna', who faced the mating ritual's fatal outcome after mating with the king of Decapod 10.
To sum Zoidberg up, he is a lobster like humanoid who seems to take the brunt of the jokes, only tasting popularity when Fry, Leela and Bender are fired.
Zoidberg is voiced by Billy West.