The narrator of Bright Lights, Big City is not named; he is in his mid-twenties and has had an upper middle class upbringing and superior, East coast education.  His aspiration is to be a famous writer, but for the moment he is working as a fact-checker at a New York-based magazine.  He is a bit lost from a failed marriage and his mother's fairly recent death, and he dives headlong into the Manhattan party scene.

Amanda is the narrator's ex-wife; she is a fashion model who leaves the narrator for another man.

The narrator has a friend, Tad Allagash, who is also fond of nightclubbing and living a dissipated lifestyle.

Clara Tillinghast is the narrator's boss, and she tends to treat him quite badly. 

Alex Hardy is a longtime writer/editor for the magazine.

Other employees at the magazine include Yasu Wade, who is amusing and derisive, Rittenhouse, Clara's favorite, Megan Avery, a down-to-earth, affable young woman, and an editor and writer called, respectively, the Druid and the Ghost. 

Characters who appear in single chapters include Michael, the narrator's brother, and Vicky, Tad's cousin. 

Let me see if I can give this one a try. I think I can list them all from memory because you're right I couldn't find a reference for you on the site. 

Unnamed Protagonist- works at a magazine as a fact checker, wife left him, abuses cocaine

Tad Allagash- best friend to the protagonist

Yasu Wade

Michael

Amanda- absentminded model who is rising fast and is the unnamed Protagonist's ex-wife

Rittenhouse

Mother-died a year earlier, Unnamed Protagonist is still reeling from the loss

Megan- coworker

Clara

Rich Vanier

Stevie/Zette

Vicky- philosophy student who Jaime dates

Kathy

Mr. Vogel

Ferret Man