Ross Jenkins

Private Ross Jenkins was a UNIT soldier during Operation Blue Sky. His call sign was Greyhound Forty.

Jenkins acted as the Tenth Doctor's escort and driver for the investigation of the Rattigan Academy and he became friendly with the Doctor. They met Luke Rattigan and the Sontaran General Staal. After losing control of an ATMOS-controlled UNIT vehicle, he and the Doctor parted ways so Jenkins could acquire another ATMOS-free vehicle to get to UNIT's temporary headquarters. (TV: The Sontaran Stratagem)

When Sontaran troops invaded the ATMOS factory, Ross was with a small group of UNIT soldiers. He had just enough time to warn the Doctor that UNIT's bullets could not harm them before being killed by Skorr for failing to hide behind a wall. His death enraged the Doctor, who intimidated Colonel Mace into ordering a withdrawal, lest UNIT suffer even worse casualties.

His death was avenged by Colonel Mace, who shot Skorr in the head three times. (TV: The Poison Sky)

Personality
Like many of UNIT's men, Ross was a loyal man who obeyed orders from his superiors without question. He respected the Tenth Doctor, believing in his final moments that the Doctor was the only one who could stop the Sontarans, though they shared a rather casual relationship while going to and from the Rattigan Academy, the Doctor referring to Ross by his first name and Ross talking to the Doctor like an ordinary man. They both agreed it was questionable that UNIT vehicles had ATMOS installed in them despite being under suspicion, with Ross showing a sharp wit and good sense of humour while doing so by saying it "[drove him] round the bend" as he was driving passed a bend, and being proud of the fact that he timed it perfectly.

He proved himself a soldier to the end, facing his death with dignity while relaying as much information as he could to the Doctor. (TV: The Sontaran Stratagem, The Poison Sky)

Behind the scenes
As revealed by writer Helen Raynor in PCOM: The Sontaran Stratagem, Ross Jenkins' name was derived from Ross Southard, script assistant, and the surname from Richard Jenkins, interactive producer of Doctor Who web content.