Horace Goodspeed brought Sayid to Oldham's tent outside the Barracks in order to determine Sayid's true identity. Oldham gave an unidentified drug to Sayid, which would apparently act as a truth serum of some sort. When Sayid started babbling about being from the future, Oldham concluded that he had dosed Sayid too heavily and did not believe Sayid's story. Oldham would appear to be the only DHARMA member who lives outside of the central Barracks complex. Sawyer describes him as a "psychopath." Oldham appears to enjoy music.
It seems highly likely that Oldham's job is to extract information from Hostiles captured by the DHARMA Initiative in their ongoing conflict. Template:Crossref
He may have been killed along with other members of the DHARMA Initiative in the Purge, possibly defected to The Others prior to The Purge, or he may have left the island by some other means.
In the episode "", Charlie tells Naomi, "My band got its start at the Night and Day bar on Oldham Street" in Manchester.
Oldham was mentioned in the part 3 of Mysteries Of The Universe by a colleague who he worked with in Los Angeles prior to joining the Initiative. The colleague also stated that Oldham was his first name, and that he was a chemist.