Doug Rattmann

Doug rattmann from Portal's 1 & 2 Doug Rattmann, also nicknamed as simply the Rat Man, was a scientist at the Aperture Science Enrichment Center. Prior to the events of Portal while GLaDOS began flooding the entire facility with neurotoxin, Rattmann is the only known employee to have survived. A paranoid schizophrenic, he is dependent on anti-psychotic medication as a means of keeping him sane.