His Majesty's Loyal Opposition (French: L'Opposition Loyale de Sa Majesté), or simply the Official Opposition (French: L'Opposition officielle), is usually the largest parliamentary opposition party in the House of Commons, either on its own or as part of a governing coalition, although, in certain unusual circumstances, it may be a third or fourth-largest party or even the largest party.

The Official Opposition is viewed as the caucus tasked with keeping the government in check. It is also generally viewed as the alternative government or "government in waiting". The Official Opposition maintains a shadow cabinet, with the leader of the Official Opposition at its head, of members of Parliament (MPs) and senators who often have the same portfolio areas of interest as actual ministers. The spokesperson for each portfolio is known as an opposition critic. In the event the government loses the confidence of the House or the Official Opposition party wins a general election, the party is ready to become the government.

The current Official Opposition is the caucus of the Conservative Party, assuming the role following the 2015 federal election. The Opposition is led by Pierre Poilievre, who became Conservative leader following the 2022 leadership election.