Phyllis Delma Dewar (March 5, 1916 – April 8, 1961), also known by her married name Phyllis Lowery, was a Canadian competition swimmer and freestyle specialist.
At the 1936 Summer Olympics in Berlin, Germany, she was a member of the Canadian relay team that finished fourth in the women's 4×100-metre freestyle relay.
In the 100-metre freestyle, she advanced to the semifinals of the event before being eliminated.
In the 1934 British Empire Games in London, she won gold medals in the 100-yard and 440-yard freestyle events and in two relays.
Four years later, at the 1938 Empire Games in Sydney, she won her fifth gold medal in the 4×110-yard freestyle relay.