Wally Mercer was a prominent lacrosse player with the New Westminster Salmonbellies during the first half of the 1930s. In 1932 he was selected to represent Canada in the lacrosse demonstration event at the Los Angeles Olympics. After losing their first match to the John Hopkins University team from the United States 5-3, they came back and defeated them 5-4, but then lost the tiebreaker 7-4; Mercer appeared in all three matches. During the 1930s, he helped found the Royal City Adanacs lacrosse club with Stu Gifford and non-Olympian Max McDonald. By career, he worked at the Provincial Mental Hospital.