Elmer Grey, FAIA (April 29, 1872 – November 14, 1963) was an American architect and artist based in Pasadena, California. Grey designed many noted landmarks in Southern California, including the Beverly Hills Hotel, the Huntington Art Gallery, the Pasadena Playhouse and Wattles Mansion. He is credited with being one of the pioneers in the development of the new American architecture in the early 20th century, with a focus on harmony with nature and eliminating features not belonging to the local climate and conditions. Grey was also a noted artist whose paintings are in the permanent collection of the Chicago Art Institute.

Grey was born in Chicago and educated in the Milwaukee public schools. He did not attend college and worked for the Milwaukee architectural firm of Ferry & Clas from 1887-1899. In 1890, the 18-year-old Grey won first prize in a competition for the design of a water tower and pumping station sponsored by a New York architectural publication. While at Ferry & Clas, he assisted in the design of the Milwaukee Central Library and the Wisconsin Historical Society in Madison, Wisconsin. When Grey went into practice on his own, he first attracted attention for his design of a summer home he built for himself on a bluff overlooking Lake Michigan at Fox Point, Wisconsin. Grey's Fox Point house was a great hit, being published widely in magazines and leading to Grey's elevation to Fellow of the American Institute of Architects.

Another major commission during his years in Wisconsin was the Christian Science church in Milwaukee. It was shortly after those plans were finished that Grey later recalled that "my health broke down completely." Grey wrote that his health problems had more to do with "nerves" rather than anything purely physical. Grey abandoned his Milwaukee practice and traveled to Florida, Philadelphia and then to Las Vegas, seeking to regain his health. He took up work on a ranch, hoping the hard work would build his strength. He eventually moved to California, spending time swimming, rowing, playing tennis and fishing on Catalina Island. When he read of a job working on a Hollywood citrus ranch for $25 a month plus board, he took the position.

In 1904, Grey became friends with a fellow Midwestern architect, Myron Hunt. The two rode horses together on Sunday mornings in Pasadena and formed a partnership in that city as Hunt and Grey. Grey later wrote that he began by working only a short time each day "until my nerves got in better shape." Grey's health again failed during the early years of his partnership with Hunt, and he took a long trip to the South Sea Islands. Yet, it was during his partnership with Hunt that Grey produced some of his finest work. The two designed fine residences for the wealthy of Pasadena and also worked on larger projects, including schools, churches and hotels. In 1905, The Architectural Record published articles on both Grey and Hunt, noting: "Both Mr. Hunt and Mr. Grey stand for the attempt to naturalize in this country the best traditions of European architecture. Mr. Grey, for instance, believes that a very genuine American style is in the process of making; but that as yet it is only in its infancy."

From 1907-1908, Hunt & Grey designed a Beaux Arts mansion for railroad and finance magnate, Henry Huntington, in San Marino. The mansion, built with reinforced concrete, tile walls and a slab roof, was not completed until 1911. In his book, "Houses of Los Angeles," Sam Watters wrote that the Huntington structure was "unique in Los Angeles for the ambition of its house." While a French influence was requested by Mrs. Huntington, Hunt & Grey also added elements of a new California architecture by including a red-tile roof, unornamented plaster walls, and sage green window trim. The Huntington mansion was later converted into the main art gallery of the cultural center built around the Huntington Library.

Hunt & Grey's larger commissions included work for Throop Institute in Pasadena, the school which would soon become California Institute of Technology. In 1911, they began plans for the new campus of Occidental College in the Eagle Rock district of Los Angeles. They also designed a dormitory and other structures for Claremont College and a master expansion plan for Pomona College.

In 1906, Hunt & Grey designed a home for Dr. Guy Cochran near Downtown Los Angeles that Gustav Stickley's The Craftsman magazine dubbed the "very best" of their work, with enormous windows "looking out upon the terrace and garden, giv[ing] such a sense of relationship between the two that there is almost no feeling of being enclosed within walls." The Craftsman referred to Hunt & Grey as "pioneers in the development of the new American architecture," which was "but a series of individual plans adapted to the climatic conditions and to the needs of daily living" and in harmony "with the natural environment and contour of the landscape." The house reflected Grey's vision of California bungalow architecture, which he described in 1907 as follows:

"The best California bungalow schemes involve a garden or large outdoor living space, incorporated as an integral part of the plan. By this we mean that the main rooms of the house are arranged to face this out-of-door living space ... It was once considered absurd to plan a house with the kitchen toward the street, but now not so in California ... the street side of [a man's] domicile is merely the side through which he enters."