HMS Janissary or Janizary was a gun-boat that served in the Royal Navy's Egyptian campaign (8 March – 2 September 1801). She appears in the records only in connection with the campaign and her origins before 1800 or service after 1801 are lost. Her name honours the Janissaries, a body of Ottoman troops.
On 2 March, while under the command of Lieutenant John Whilley, Janissary, together with the cutter Cruelle and the gun-vessel Dangereuse, protected the left flank during the landing of troops in Aboukir Bay.[1] The cutterEntreprenante, schoonerMalta, and the gun-vessel Negresse covered the right flank.[1]Janissary's officers and crew therefore qualified for the clasp "Egypt" to the Naval General Service Medal that the Admiralty authorised in 1850 to all surviving claimants.[2]