|“||Sir, Samus's ship has joined the fleet.||„|
The Ensign is a crew member on board the G.F.S. Olympus. He is a generic Male Fleet Trooper stationed to the left in the Flag Bridge. Before the Olympus follows the captured Leviathan Battleship into a wormhole to Phaaze, he briefly speaks to Fleet Admiral Castor Dane to inform him of Samus' arrival. He is unseen in the cutscene.
The name likely refers to the character's rank
-  YouTube video of the scene.