Leutnant Wilhelm Fahlbusch (8 February 1892 – 6 September 1916) was an early World War I flying ace credited with five aerial victories, shared with his observer Hans Rosencrantz.

"Willi" Fahlbusch was that rarity in the Luftstreitkräfte, a reconnaissance pilot who became an ace.

He flew as a member of Kasta 1, teamed with Hans Rosencrantz in a Roland Whale.

They were credited with five aerial victories during 1916, with the last being scored on 31 August 1916 over a British Martinsyde Elephant two-seater craft.

The German duo were shot down in flames over Malincourt, with three British air crews posting victory claims.