Sir Michael Patrick Cashin (1864-1926) was a businessman and politician. Cashin entered business as a fishing merchant but became rich as a salvage merchant earning him the nickname "King of the Robbers" for his south shore salvage operations. He was elected to the legislature in 1893 as an independent but worked closely with the Liberal Party. In 1907 he joined the Newfoundland People's Party of Sir Edward Morris and became minister of finance in 1909. When Morris resigned as party leader Cashin succeeded him. The People's Party had formed a wartime national government which opposition member William F. Lloyd, a Liberal, had joined as minister of justice.

Despite the fact that Cashin had succeeded Morris as leader of the dominant party, the governor appointed Lloyd to the position of Prime Minister. On May 20, 1919, Cashin, who was still minister of finance, rose and moved a Motion of No Confidence in the government he was a member of. The motion passed and Cashin became Prime Minister.

Cashin's government was short lived however, the House of Assembly had not seen an election for six years due to the First World War and a return to the polls was long overdue. An election was held in November 1919 which defeated Cashin's government and elected the opposition Liberals (now called the Liberal Reform Party).

In opposition Cashin changed the name of the People's Party to the Liberal-Labour-Progressive Party before retiring as party leader in 1923. He did not run for re-election in 1924.

Cashin's son, Peter John Cashin, was a prominent Newfoundland politician in his own right and his grandson, Richard Cashin was a federal politician in the 1960s and a trade union leader in the 1970s and 1980s.