James Joseph Speyer (July 22, 1861 – October 31, 1941)[1] was an American banker based in the city of New York.

[4] While initially a substantial financial powerhouse, Speyer & Co. began a decline when World War I started in 1914.

During the interwar period, the decreasing value of rail stocks, the United States' rise as a creditor nation, and official anti-Semitism in Germany contributed to further decline of the Speyer interests.

Speyer's one-man-show management style was also a factor in the decline as well as his varied interests, which limited the time he gave to his banking concern.

By 1899, Speyer had de facto control of both the Central and Southern Pacific Railroads, control that allowed him to block Collis' nephew Henry from the presidency of the Southern Pacific following Collis' death and ultimately to force the younger Huntington to sell his interests in the SP to E. H.

Much of this activity was centered at Waldheim, their country home at Scarborough-on-Hudson, along which property ran a portion of that aqueduct.

This interest interfered with his work on behalf of the Salvation Army, which was unalterably opposed to liquor in any form.