Velcro
Swiss electrical engineer George de Mestral invented his first touch fastener when, in 1941, he went for a walk in the woods and wondered why Burdock seeds clung to his coat and dog. He discovered it could be turned into something useful. He patented it in 1955 and subsequently refined and developed its practical manufacture until its commercial introduction in the late 1950s.
William Sellers
William Sellers (September 19, 1824 – January 24, 1905) was a mechanical engineer, manufacturer, businessman, and inventor who filed more than 90 patents, most notably the design for the United States standard screw thread. As president of the Franklin Institute in Philadelphia, Pennsylvania, Sellers proposed the adoption of a system of screw threads which was easier for ordinary mechanics and machinists to cut than a similar design by Joseph Whitworth. For many years, he led the machine tool firm of William Sellers & Co., which was a very influential machine tool builder during the latter half of the 19th century.