Staal

Staal the Undefeated was a Sontaran and General of the Tenth Sontaran Battle Fleet during the invasion of Earth in 2009. He had a great love of warfare and regretted that his race were not involved in the Last Great Time War, which he considered to be one the universe's greatest wars. He forged an alliance with Luke Rattigan to aid the Sontaran conquest of Earth. He had an ambition to personally kill the Doctor upon meeting him, partially due to the Doctor's enemity with the Sontaran race and Staal's grudge over not being allowed to fight in the Time War. (DW: The Sontaran Stratagem)