Walter Brown Gibson (September 12, 1897 – December 6, 1985) was an American writer and professional magician, best known for his work on the pulp fiction character The Shadow. Gibson, under the pen-name Maxwell Grant, wrote "more than 300 novel-length" Shadow stories, writing up to "10,000 words a day" to satisfy public demand during the character's golden age in the 1930s and 1940s. He authored several novels in the Biff Brewster juvenile series of the 1960s. He was married to Litzka R. Gibson, also a writer, and the couple lived in New York state.

Gibson is recognized as the creator of much of The Shadow's mythos, although his tales often conflict with the better-known radio show version. For example, Gibson's Shadow is, in reality, Kent Allard, a former World War I aviator, who sometimes posed as playboy Lamont Cranston. On the radio show, The Shadow was Cranston, a "wealthy young man about town." Similarly, Shadow companion Margo Lane arose not from the pulp novels but from the radio program; she was added to offer a contrasting female voice to the show's audience. In 1941 Gibson grudgingly added Margo Lane to the pulp stories, and even hinted at her having a power of invisibility.