The XB-59, Boeing model number 701, was a 1950s proposal for a United States supersonic bomber aircraft.

Developed under weapons system designation MX-1965, the XB-59 was to have a crew of three, and would be powered by four GE J73-X24A turbojet engines, mounted in the roots of the wings. The landing gear would be similar to the bicycle arrangement found on the B-47 Stratojet and B-52 Stratofortress, with wingtip-mounted outriggers.

The Boeing contract for the XB-59 was canceled in late 1952 after the Convair company's submission, designated B-58 Hustler, was selected for development.

The Boeing effort was a design study only, and no construction was involved.