Captain John McDonell (c. 1758-21 November 1809) was a soldier, judge and political figure in Upper Canada following the American Revolution. He was elected as the first speaker for the Legislative Assembly of Upper Canada.
John McDonell was born at Aberchalder Lodge in Scotland, a son of Alexander MacDonell. In 1773, he came to the Mohawk Valley of New York with his father and uncles.
In 1775, during the American Revolution, McDonell was commissioned in the Royal Highland Emigrants. On 1 August 1778, he transferred to John Butler's Rangers. For a time, he served as paymaster at Fort Niagara.
When the Treaty of Paris ended the American Revolution in 1783, McDonell settled with other Highlander Loyalists along the Saint Lawrence River in Upper Canada. He was appointed to the land board for the Lunenburgh District in 1788 and later for Glengarry & Stormont in 1792. He was appointed to the Court of Common Pleas and the district Court of Quarter Sessions. He was also named lieutenant for Glengarry County in 1792. He played an important role in the local militia, commanding the Upper Canada Battalion of the Royal Canadian Volunteer Regiment.
In 1792, McDonell and his brother Hugh McDonell were elected to the Legislative Assembly representing Glengarry. John McDonell was chosen speaker. He was reelected in 1796, but was unable to attend until 1798 due to illness.