(Capcom's primary storyline)
Dr. John Clemens was a scientist who was employed by Umbrella Pharmaceuticals. When Dr. William Birkin was reassigned to NEST, Clemens took over as the chief of research at the Arklay Laboratory, a top secret laboratory built beneath a mansion façade.
Clemens worked in the 1980s as a researcher at Umbrella USA's Chicago headquarters. Some time between 1991 and 1995, Clemens was transferred to the Arklay Laboratory outside Raccoon City, where he was to take over Dr. William Birkin's role as chief of research. While a brilliant scientist, Clemens did not have the stomach for Umbrella's illegal weapons research, which Umbrella considered a negative personality trait. A rumour among Umbrella Intelligence Division operatives was that in the event of an information leak he would be the primary suspect.
Around 1998, a rival company infiltrated Umbrella USA and planted Ada Wong as a researcher to send back information. Wong and Clemens built up a relationship, which Clemens was serious about and was well known to other members of staff. Believing Wong to the very end, Clemens also used her name as his personal password.
When the t-Virus escaped containment, Clemens was infected, and in his last moments wrote a letter to Ada giving information on how to activate the facility's self-destruct system, telling her to take evidence of Umbrella's experiments and expose them to the public. Unable to take his own life before turning into a zombie, Clemens also instructed Ada to kill him if she found him in this state. Instead, his letter and zombified body were found by S.T.A.R.S., once that Ada had already escaped the facility. Ada never got to read the letter, having discovered Clemens' final fate only during the Raccoon City outbreak upon being informed by Annette Birkin.
- In S.D. Perry's novelization of Resident Evil, John is given the surname "Howe". It should be noted that the S.D. Perry novels have their own separate canon outside of the games, and should not be used as fact when referring to characters in the games.
- John appears as "John Marcus" in George A. Romero's unproduced Resident Evil movie script, and is killed in the opening. His relationship with Ada Wong is maintained.
- In the remake, in Researcher's private room B there is a zombie inside which probably was Clemens himself. This is reinforced by the fact that his letter is in the X-ray room, which is nearby.
- Wesker's Report II.
- Emergency report
- Resident Evil (2002), file: "Letter of a Researcher".
- Resident Evil 2 (1998), dialogue:
Annette Birkin: "Ada Wong? I've heard that name before. Now I remember. One of the men from Chicago who came to assist the t-Virus research used his girlfriend's name as his password. 'Ada' and 'John', I believe."
- Resident Evil 2 (1998), scene: Women squaring off (Leon B)
- Resident Evil: The Umbrella Conspiracy