Who was the first test pilot for the ME 262 aircraft?

Hans Guido Mutke, in 1944. He did signifigant damage as the aircraft approached 1,200 miles per hour. He is considered to be the first person to fly faster than the speed of sound, even though eyewitnesses state that he never broke the sound barrier.

The ME 262 was the world's first jet aircraft, created by Nazi Germany. It saw brief service in WWII intercepting bombers.