Nelson - destroyed Franco Spanish Fleet as well as French ambitions and the French fleet in the Med at Aboukir.
Drake - Destroyed Spanish Armada with some help from the weather.
ABC Cunningham - took on the Italians and Germans in the Med in WW2, who had a far superior and modern fleet compared to our WW1 era battleships. Yet he won, which enabled Monty to win North Africa and the allies to land in Africa/Italy/S.France. Had the Axis taken Suez and the oil fields and thrown Blighty out the Med WW2 may have been a bit more difficult.
Honourable mention to Captain Walker for u-boat attack techniques and Hood and Rodney for duffing up the French again.
Apart from a few setbacks with the Dutch I don't think there's any other Europeans who've moulded the sea with major battles like the pesky Brits, even with unbiased hindsight.
As for Ancient History my knowledge is sketchy, but I think Lysander for defeating Athens and Themistocles for Salamis.