As decades pass, fans of the Brooklyn Dodgers, perhaps the most fervidly nostalgic partisans in the history of sports, are growing fewer and fewer. The 2016 baseball season, now getting underway, is the 59th since the team decamped to Los Angeles, leaving Brooklyn’s baseball die-hards with pangs of heartsickness for the loss of Gil Hodges, Duke Snider and Pee Wee Reese and venomous animosity for the never-to-be-forgiven betrayal of the team owner, Walter O’Malley, who took them away.

Of their ever-diminishing number, perhaps one man stood out above all: Tom Knight, the first and only official baseball historian of Brooklyn.

Mr. Knight, who died at 89 on Feb. 17 in Brooklyn, where he lived his entire life except for time in the Army, was appointed to his unpaid post in 1976 by Sebastian Leone, then the Brooklyn borough president. It’s not certain that he had any official duties, but his qualifications were indisputable. Mainly it was this one: He knew everything about the Dodgers. (About most other teams, too.)

Mr. Knight had an enormous memorabilia collection. He gave tours of Brooklyn baseball landmarks that included not only the site of Ebbets Field, home of the Dodgers from 1913 until they left town (it was demolished in 1960), but also, in Green-Wood Cemetery, the grave of Charles Ebbets, who owned the team in the early 20th century.