Captain David D. "Dave" Dubosky, aka Countdown, is a member of G.I. Joe. Serving as the Joe team's resident astronaut, Countdown is an expert pilot and electronics engineer, able to fly an F-16 with one hand and repair broken instruments with the other. Despite these incredible abilities, the rest of his teammates see him as incredibly boring.
Dave Dubosky was a member of the Earth Defense Command who was secretly a Dire Wraith in disguise. After infecting the lone survivor of a military unit ordered to engage Rom upon his arrival, Dubosky met with some of his former G.I. Joe teammates to hunt down the Space Knight.
Dubosky later found and retrieved Darby Mason. When Dubosky questioned her about Rom, Mason remained coy about the details, unsure of whether to trust him. Dubosky gave her a special gun and phone to protect herself and get in contact with him. Mason later used that phone to report to Dubosky that she had found Camilla Byers and Rom.
Countdown's G.I. Joe dog tags were later recovered from Mount Olympus by the current Action Man, Ian Noble, who received them from former G.I. Joe member Big Ben. Ian reported this to Mainframe, who insisted that Dubosky being there was impossible, having spoken to him mere minutes ago.