Sir Samuel Leonard Tilley PC KCMG CB (May 8, 1818 – June 25, 1896) was a Canadian politician and one of the Fathers of Confederation. Tilley was descended from United Empire Loyalists on both sides of his family. As a pharmacist, he went into business as a druggist.

Sir Samuel Leonard Tilley was born in Gagetown, New Brunswick, on May 8, 1818, to a storekeeper named Thomas Morgan Tilley, and Susan Ann Peters, both of whom had descended from American loyalists.

Samuel Leonard Tilley entered politics as an activist in the temperance movement. As a result of the 1848 recession, caused in part by Britain's economic policies, he became an advocate for responsible government. Tilley later joined the New Brunswick Colonial Association, which advocated for the colony's own control over its public expenses, the establishment of a public school system, government control of public works, and "honest government" in general.

First elected to the New Brunswick Assembly as a Liberal in 1850, he sat in opposition until the 1854 election swept the reformers to power. Tilley became Provincial Secretary in the government of Charles Fisher. In 1855 he persuaded the assembly to pass a prohibition law, but that proved a failure and was later repealed.

He attended each of the Charlottetown, London, and Quebec City Conferences as a supporter of Canadian Confederation. He served as premier of the colony of New Brunswick from 1861 until his government was defeated in the election of 1865. As premier, he supported the New Brunswick's entry into Confederation and the construction of an intercolonial railway.

A common tale states that Tilley was the originator of the word "Dominion" in Canada's name. The Fathers of Confederation had been discussing what to prefix Canada with, Kingdom of Canada being Macdonald's preference. During morning devotions, Tilley read Psalm 72:8, which states "He shall have dominion also from sea to sea, and from the river unto the ends of the earth", and presented this inspiration to the others, being as their ambition was to stretch the new nation to the Pacific Ocean and from the St Lawrence River to the North Pole. "Dominion" had been used before, but Tilley pushed hard for it to be adopted in reference to Canada, despite Macdonald's preference.

The term led to the naming of the July 1 national holiday; however, the reference to a unique Canadian historical development was discarded in 1982 when "Canada Day", which had already been in use by most Canadians, was made official by an act of Parliament. In French, the date had long been known as la fête nationale (national feast or national birthday), a date which is often now applied to June 24 in Quebec, a date officially known as Saint-Jean-Baptiste Day.

Tilley entered federal politics with Confederation in 1867 and served in the federal cabinet as Minister of Customs. He became Minister of Finance in 1873 and served until the defeat of the government later that year. He was appointed the fourth Lieutenant Governor of New Brunswick in 1873 and served until 1878. When Macdonald's Tories returned to power in 1878, Tilley was elected member for Saint John and again became minister of finance; while in that office he introduced protective tariffs which became the basis of Canadian financial policy. He served in cabinet until his retirement from politics in 1885, when he was again appointed the seventh Lieutenant Governor of New Brunswick.