William Frederick Crothers (born December 24, 1940 in Markham, Ontario) is a retired Canadian track and field athlete.
At one point, he held the Canadian record in all distances from 400 metres to 1500 metres and was holder of the world 800 metre indoor record. In 1963, he ran the two fastest 800 metre races of the year. He was named Lou Marsh Trophy winner as Canada's top athlete of 1963. Crothers competed for Canada in the 1964 Summer Olympics held in Tokyo, winning a silver medal in the 800 metres. He also competed in the 400 metres, but was eliminated in the semi-finals. He received the Lionel Conacher Award as Canada's top male athlete of 1964. Crothers was ranked by Track & Field News as the top 800 metre runner of 1965 and the second best of the decade.
He has been inducted into the Canadian Olympic Hall of Fame (1965), and Canada's Sports Hall of Fame (1971).