An agent-general is the representative in cities abroad of the government of a Canadian province or an Australian state and, historically, also of a British colony in Jamaica, Nigeria, Canada, Malta, South Africa, Australia or New Zealand and subsequently, of a Nigerian region. Australia's and Canada's federal governments are represented by high commissions, as are all Commonwealth national governments today.

In the Commonwealth of Nations, a high commissioner is the senior diplomat, generally ranking as an ambassador, in charge of the diplomatic mission of one Commonwealth government to another. Instead of an embassy, the diplomatic mission is generally called a high commission.