Peter Lymburner Robertson (December 10, 1879 – September 28, 1951) was a Canadian inventor, industrialist, salesman, and philanthropist who popularized the square-socket drive for screws, often called the Robertson drive. Although a square-socket drive had been conceived decades before (having been patented in 1875 by one Allan Cummings of New York City, U.S. Patent 161,390), it had never been developed into a commercial success because the design was difficult to manufacture. Robertson's efficient manufacturing technique using cold forming for the screw's head is what made the idea a commercial success. He produced his screws (patented in Canada in 1909) in his Milton, Ontario, factory starting in 1908. The brand has been sold over the years, and the manufacturing for the present corporation (Robertson Inc.) is done in Jiaxing, Zhejiang, China; but the Milton, Ontario, building was still a head office for a long time before moving to nearby Burlington, Ontario.