John William Merrow (August 15, 1874 – April 11, 1927) was a New York City theater architect.
John William Merrow, son of Moses H. and Ella R. A. (Proctor) Merrow, was born in New Hampton, New Hampshire. Known throughout his life as "Will," to distinguish him from his better-known uncle, John Francis Merrow, he graduated from New Hampton Literary Institute (now known as New Hampton School) in 1892 and from the New Hampton Commercial College in 1893. He graduated from Dartmouth College in 1897 with an A.B. degree and later attended the architectural course at the Massachusetts Institute of Technology.
His first professional association was with the architectural firm of Wheelwright & Haven in Boston, Massachusetts. In 1900, he was the architect of the East Blue Hill Library in East Blue Hill, Maine, designed in the American Craftsman style. In 1990, this structure was added to the National Register of Historic Places. Also in 1900, he redesigned the interior of the New Hampton Community Church on Main Street in New Hampton, New Hampshire.
He was employed by his uncle Frederick Freeman Proctor (popularly known as "F. F. Proctor"), owner of Proctor Theatrical Enterprises in New York City, designing and "supervising the building of numerous theatres in and out of the city, in addition to keeping all of the houses owned by Mr. Proctor up to modern requirements and standards". In 1905, he was the architect of Proctor's Palace Theatre and Proctor's Palace Roof Theatre, on Market Street between Halsey and Washington Streets, in Newark, New Jersey. This was one of the rare "double decker" theatres, an eight-story complex with a large 2,300-seat theatre at ground level and a smaller theatre of about 900 seats occupying the top four floors beneath the roof. This theatre is described more fully in Warren G. Harris's article under Frederick Freeman Proctor.