Who is the fastest male 800 meter runner?

Bolt

Bolt is wrong, bolt runs the 100 (9.58) 200 (19.19) and the 4x100 (37.90)

The actual answer is Hicham El Guerrouj. He holds the world record for the 1600 meter run with a time of 3:43.13. Furthermore, the 3:43.13 was timed for a mile, which is 9.35 meters further than 1600 (which he had passed about a second and a half earlier).