Which author used the pseudonym 'Ed McBain'?

Evan Hunter used the pseudonym Ed McBain.

Hunter was born Salvatore Albert Lombino in New York City in 1926 and legally adopted the name Evan Hunter in 1952. He used several pen names during his career, but Ed McBain became his best-known crime-fiction identity. The name first appeared on Cop Hater, published in 1956 as the opening novel of the 87th Precinct series.

Writing as McBain allowed Hunter to separate his police procedurals from the novels and screenwriting he published under his own name. The 87th Precinct books portray detectives working in the fictional city of Isola, a setting closely modeled on New York. Their emphasis on teamwork, routine investigation, evidence, and competing viewpoints helped make the series a major example of the police-procedural genre.

Hunter publicly revealed the connection in 1958 but continued using Ed McBain for decades. He also wrote as Richard Marsten, Curt Cannon, Hunt Collins, John Abbott, and Ezra Hannon. Readers sometimes confuse McBain with Mickey Spillane or Donald Westlake, but those were separate American crime writers with their own names and characters.