Valdez

An ODST Marine in the UNSC, "Doc" Valdez was an enlisted medic with the ODST detachment for the UNSC Pillar of Autumn in 2552.

When the vessel fled The Battle of Reach and ended up at Installation 04, Valdez tended to the wounded and dead as the Covenant began to board the ship. He, along with the rest of the ODSTs, defended the engine room, where he treated First Lieutenant Melissa McKay for a plasma burn on her arm.

His rank and first name were never given, nor was he ever mentioned again, but we can assume that he "helljumped" to the surface of the installation, helped attack and defend Alpha Base, and was killed somewhere along the way.

Because most medics in the UNSC Marine Corps are Navy Corpsmen, not technically Marines, Valdez may have been a Petty Officer. He was the senior medic in a platoon in McKay's B Company, so he was probably a Petty Officer 2nd or 1st class, the equivalent of a sergeant or staff sergeant.