William Molloy (October 28, 1877^[1] – April 10, 1917^[2]) was a politician in Manitoba, Canada. He served in the Legislative Assembly of Manitoba from 1910 to 1914 as a member of the Liberal Party.

He was born in Arthur, Ontario, the son of John Molloy^[1] and Mary Alice Daly,^[3] came to Manitoba with his family in 1879 and was educated at the University of Minnesota. At first, Molloy taught school in Manitoba; he later was employed as a land surveyor.^[1]

Molloy was elected to the Manitoba legislature in the 1910 provincial election, defeating Conservative incumbent Jean-Baptiste Lauzon^[4] by seven votes in the rural constituency of La Verendrye. The Conservatives won the election, and Molloy served in the legislature as a member of the opposition. He was defeated in the 1914 election, losing to Conservative Jacques Parent^[4] by 262 votes in the Morris constituency.

Molloy attempted to return to the legislature in the 1915 election, but lost to Parent^[4] by 57 votes.

His brother John was a member of the Canadian House of Commons^[1] and his brother Thomas served in the Manitoba assembly.^[3]

Molloy served in the Canadian Expeditionary Force as a lieutenant during World War I. He died while serving overseas with the 1st Canadian Mounted Rifles (Saskatchewan) and was buried in France.^[2]