Master Humphrey is the narrator and main character in Dickens's serial

Serial (literature)

In literature, a serial is a publishing format by which a single large work, most often a work of narrative fiction, is presented in contiguous installments—also known as numbers, parts, or fascicles—either issued as separate publications or appearing in sequential issues of a single periodical...

, Master Humphrey's Clock

Master Humphrey's Clock

Master Humphrey's Clock was a weekly periodical edited and written entirely by Charles Dickens and published from April 4, 1840—December 4, 1841. It began with a frame story in which Master Humphrey tells about himself and his small circle of friends , and their penchant for telling stories...

. He is also the unnamed narrator of the first three chapters of Dickens's The Old Curiosity Shop

The Old Curiosity Shop

The Old Curiosity Shop is a novel by Charles Dickens. The plot follows the life of Nell Trent and her grandfather, both residents of The Old Curiosity Shop in London....

which was originally published in that serial. It is revealed in the portion of Master Humphrey's Clock which follows The Old Curiosity Shop that he is also in fact the unnamed 'single gentleman' who appears in the second half of that novel.