Walter Thiel (March 2 1910 - August 17 1943) was a German engineer who largely designed the rocket engine that powered the V-2 missile.

Thiel was born and grew up in Breslau. He studied materials engineering at the Technical University there and became intrigued by the potential of hypergolic fuels for rocketry.

He joined Wernher von Braun's team at Peenemünde in 1936 and provided the breakthrough that made the V-2 possible when he decided to use turbopumps to feed fuel into the rocket engine. Engine designs prior to this had relied on pressurization of the fuel tanks to drive the fuel out when a valve was opened. Thiel's refinement led to a ten-fold increase in power. With Klaus Riedel, Thiel also worked to refine the combustion chamber and nozzle design.

Thiel and his family were killed in the RAF air raid on Peenemünde on the night of 16-17 August 1943 (Operation Hydra ).