Bartleby.  The three other workers - Turkey, Nippers, and Ginger-Nut - all have character traits that indicate they have passions and lives outside of work.  However, the focus of the plot is on Bartleby's inability to find a purpose in life, to find something he prefers to do.  Work is all he is.  Similarly, the narrator is only known to us as a lawyer, suggesting that  he, too, has little life beyond work.  This could be the reason he is so captivated by Bartleby, because he sees himself in this other man.

Though we often think of the protagonist as the lead character in a story, a protagonist can also be an important character or a character, according to the Merriam-Webster dictionary, who is the "supporter of a cause."

Given this definition, the narrator is definitely a protagonist in the story. He is not only telling Bartleby's story but has an important role in it. A lawyer, he hires Bartleby to do copying, and for a long time after Bartleby decides he "prefers not to" do anymore work, tolerates his presence in the office. Even when the lawyer feels forced to move offices and Bartleby ends up in the Tombs, the city jail, the lawyer visits him and tries to ensure he is well taken care of.

Bartleby takes up a disproportionate amount of the lawyer's attention, and the lawyer feels a sympathy for him an average employer would not for an employee who stopped doing any work. Because the lawyer is telling the story, we also feel a good deal for sympathy for and curiosity about Bartleby. The lawyer has the sensitivity to perceive that Bartleby is a troubled soul. Rather than write Bartleby off as crazy, the lawyer becomes a "supporter of [his] ... cause."

The lawyer even continues to be curious about and investigate Bartleby after his death, discovering his job at the Dead Letter Office in Washington. He fashions Bartleby for us as a symbol of the wider human inability to communicate effectively.

The beginning of this story introduces us to the narrator. It is clear from the opening sentence that this is a man who has reached the end of his career, and he is somebody who has enjoyed a comfortable and successful existence without having had to work too hard. This is something he stresses, saying:

I am one of those unambitious lawyers who never addresses a jury, or in any way draws down public applause; but in the cool tranquillity of a snug retreat, do a smug business among rich men's bonds and mortgages and title-deeds.

Given what occurs later, we can understand how the case of Bartleby has stayed with him for so long. He describes the law office where he worked for so long, and his various employees before he employed Bartleby. However, the introduction makes it clear that Bartleby is the main focus of this tale:

But I waive the biographies of all other scriveners for a few passages in the life of Bartleby, who was a scrivener the strangest ever saw or heard of. While of other law-copysists I might write the complete life, of Bartleby nothing of that sort can be done... Bartleby was one of thos beings of whom nothing is ascertainable, except from the original sources, and in his case those are very small.

This story then is an attempt of its narrator to "ascertain" Bartleby as much as possible based on the scant evidence he has access to. The narrator of this story therefore begins this tale almost as if it were something of a mystery. He introduces those involved and then also introduces the central character, who he will present to us in his efforts to work out his significance.