Magogg
Magogg was a Ratling sniper who fought in the Damocles Gulf Crusade in 742.M41, accredited with the first known kill of a Tau Ethereal.
During the advance on Gal'bryn City, the Tau capital of the Sept World of Dal'yth, Magogg and his squad were scouting ahead of the main Imperial Guard advance. They spotted a Tau armoured column consisting of grav tanks moving cautiously towards the Imperials' flank. The column halted, to the ratlings' amazement, only 300 metres from their concealed position.
During this time, Magogg surveyed the Tau as they disembarked through his rifle's scope. He watched the Tau in conversation with one of their own in long, flowing robes. Deducing that that particular xeno was an officer or leader of some sort, he proceeded to blow the Tau's head clean off.1
The Tau column went into instant disarray, panic and confusion going unchecked. In addition to saving the Imperium's flank, Magogg achieved the first recorded kill of a Tau Ethereal, teaching the Imperium a valuable lesson in fighting the newly discovered aliens.1