Nicholas Nickleby; or, The Life and Adventures of Nicholas Nickleby is a novel by Charles Dickens. Originally published as a serial from 1838 to 1839, it was Dickens' third novel.

The novel centers on the life and adventures of Nicholas Nickleby, a young man who must support his mother and sister after his father dies. His Uncle Ralph, who thinks Nicholas will never amount to anything, plays the role of principal antagonist.

'Nickleby' marks a new development in a further sense as it is the first of Dickens' romances. When it was published the book was an immediate and complete success, and established Dickens's lasting reputation.

The cruelty of a real Yorkshire schoolmaster named William Shaw became the basis for Dickens's brutal character of Wackford Squeers. Dickens visited his school and based the school section of Nicholas Nickleby on his visit.

Like many of Dickens' works, the novel has a contemporary setting. Much of the action takes place in London, with several chapters taking place in Dickens' birthplace of Portsmouth, as well as settings in Yorkshire and Devon.

The tone of the work is that of ironic social satire, with Dickens taking aim at what he perceives to be social injustices. Many memorable characters are introduced, including Nicholas' malevolent Uncle Ralph, and the villainous Wackford Squeers, who operates an abusive all-boy boarding school at which Nicholas temporarily serves as a tutor.