Leopold Bloom is a fictional character in James Joyce's novel Ulysses. He is a Jewish advertising agent introduced to us at the very beginning of episode 4 (Calypso) of the novel, with the following words:

Mr Leopold Bloom ate with relish the inner organs of beasts and fowls. He liked thick giblet soup, nutty gizzards, a stuffed roast heart, liverslices fried with crustcrumbs, fried hencods' roes. Most of all he liked grilled mutton kidneys which gave to his palate a fine tang of faintly scented urine.

Ulysses is primarily focused on Bloom and the micro-odyssey he embarks upon throughout Dublin over the course of the single day of June 16, 1904 (though episodes 1 to 3 are more concerned with Stephen Dedalus), the various types of people and themes he encounters. Among Joyce afficionados, June 16th is celebrated as Bloomsday.

Throughout the novel Bloom is aware of an affair his wife Marion is having with the go-getting singer Blazes Boylan, and broods about the death of his child, Rudy. He also demonstrates his chauvinistic attitudes, a penchant for voyeurism and his unfaithful pseudonym, Henry Flower, whom he promptly destroys almost as soon as we discover him.