Admiral Sir Michael Seymour, GCB was a Royal Navy officer who went on to be Commander-in-Chief, Portsmouth.

The Commander-in-Chief, Portsmouth, was a senior commander of the Royal Navy for hundreds of years. The commanders-in-chief were based at premises in High Street, Portsmouth from the 1790s until the end of Sir Thomas Williams's tenure, his successor, Sir Philip Durham, being the first to move into Admiralty House at the Royal Navy Dockyard, where subsequent holders of the office were based until 1969. Prior to World War I the officer holder was sometimes referred to in official dispatches as the Commander-in-Chief, Spithead.