Robert James Manion PC MC (19 November 1881 – 2 July 1943) was a Canadian politician who led the Conservative Party of Canada from 1938 to 1940.

A Liberal prior to World War I, Manion was elected to the House of Commons in 1917 as a member of the pro-conscription Unionist Party led by Prime Minister Robert Borden.

A member of the Liberal Party before the war, he supported Conservative Prime Minister Robert Borden's pro-conscription Union government that was formed as a result of the Conscription Crisis of 1917.

According to historian Roy Piovesana, Manion's loss was partly attributable to his failure to cultivate his Fort William riding.

Manion moved the Conservatives to the left and was criticized as a socialist due to his call for action against unemployment and his desire to, in his words, "bring a greater measure of social justice to all our citizens.

"[1] He hoped to come to power due to the criticism the King government was facing after the brokerage of an agreement with the Union Nationale Premier of Quebec, Maurice Duplessis in which he promised federal funds for unemployment relief in Quebec in exchange for the Union Nationale's support for the Conservatives in the federal election.

[1] The defeat of the government of Maurice Duplessis in Quebec dashed Manion's hopes of building an electoral alliance with the conservative premier.

Therefore, the Liberals won a second consecutive landslide majority government, the renamed Tories were unable to make any gains from their 1935 result, and Manion failed to win his seat, leading to his resignation as party leader two months later.