D-9341 is a disposable class personnel housed at the SCP Foundation, an extremely secretive organization who contains and analyzes dangerous, supernatural entities labelled SCPs, using death row inmates to test these creatures. The nameless D class appears as the faceless silent protagonist of the indie video game adaption of the Foundation, SCP: Containment Breach.
Absolutely nothing is known about D-9341's past, though since he is a D class, it is assumed that he was a criminal who has a done a crime(s) heinous enough to be put on death row (however, he could've been falsely accused). After being escorted to Euclid classified SCP-173's containment chamber to do some tests on it with another pair of D classes, a power outage ultimately led to a huge containment breach among the facility. Fitted with nothing but an orange prisoner jumpsuit, D-9341 is forced to navigate his way through the Foundation with thousands of inhumanly dangerous anomalies hunting him down.
After this, the D's story is left up to the player, but he is usually characterized to befriend SCP-079 to help him escape. There are two endings to the game. The first ending, considered the bad one, is on Gate B, where SCP-682 (one of the most dangerous SCPs) escapes and the facility is forced to nuke the entire base, killing all including the player. However, if the player turned off the warheads earlier in the game, MTF units and helicopters will swoop down and execute the defenseless D. The second, "good" ending, on Gate A, is when SCP-106 makes a run for it out of the facility, where he is quickly gunned down by the MTF's light cannon and sent back to his dimension. SCP-106's escape gives the player time to slip past the hostile MTF unnoticed and flee the facility, only to get captured by the Foundation's rival organization, the Chaos Insurgency.
D-9341's face, name, build, and history has never been revealed, leaving him an enigma amongst the player. He was originally even thought to be a female, as he only spoke through text boxes in his head, but this was disproved when he spoke aloud in a clear masculine, noticeably young, voice.
From the 2 Gate A endings... it is implied that D-9341 has supernatural abilities, activated when the MTF units entered the service tunnel, causing it to cave them in... and when the MTF capture him, he was considered to Obtain SCP classification. although this is for his high amount of luck, and surviving certain death on multiple occasions.