Baron Klas Kristersson Horn (1517 – September 9, 1566) was a Finnish-born Swedish nobleman and naval admiral who fought for Sweden in the Northern Seven Years' War of 1563–1570.

In 1550, King Gustav I of Sweden made him the head of the district of southern Finland at Raseborg.

In 1559, he won a number of battles against Danish naval forces under Herluf Trolle and the Free City of Lübeck.

After Jakob Bagge was captured, Klas was promoted to admiral in the Royal Swedish Navy in the fall of 1564.

He died at Stora Åby parish in Östergötland, Sweden and was buried at Uppsala Cathedral.