Terrance Jackson aka Theo Noble was a student of Arthur Strauss and later became an ally of Dr. Strauss.
Theo is a student of Arthur Strauss and considered his star pupil. He first met Strauss at a hospital while looking for medical supplies. Strauss found and helped him and aided Theo in finishing his murder. The two remained close for thirteen years.
Thirteen years after meeting Strauss, Theo returned to help free his former mentor by hacking the FBI. Later on he met up with Strauss under the pretense of giving him new identification and passports to flee the country. This however proved to be a ruse so that he could kill Strauss for making him come out into the open.
- November 14, 1990, Philadelphia, Pennsylvania: His mother and his two brothers (All hacked to death with a machete by the Madman killer; murder by proxy)
- 1996, Philadelphia, Pennsylvania: His mother's abusive boyfriend
- At least three victims killed by gunshot, stabbing and strangulation between 1996 and 2002
- At least 30 victims killed in staged murder-suicides
- 2002, East Providence, Rhode Island:
- Patrick (tied up, shot once in the head, made to look like a suicide framed for a mass murder)
- At least twelve people in an office park (shot them with a shotgun)
- March 2015:
- New York City, New York: Nathan Rhodes (presumed; possibly burned to death with a blowtorch)
- Beacon, New York: Arthur Strauss (strangled to the point of near beheading)
- unspecified location in New York: U.S. Marshals Corey and Gillian P. (Both hacked to death with a hatchet)
- New York City, New York: Three of Luis Serra's friends (All hacked to death)
- Kent (stabbed once)
- Tucker Moore (strangled)
- Baltimore, Maryland: Nancy and Bob Gibbs (both shot; made to look like a murder-suicide)
- Baltimore, Maryland: His family:
- Cindy Noble (drugged and her wrists slashed)
- Oli and Rose Noble (both non-fatally drugged)
- New York City, New York: A security guard (throat slashed)
- Waynesboro, Virginia: U.S. Army Captain Robert James Tubbs (shot once in the head)
- Newark, New Jersey: Josh (stabbed)
- Hoboken, New Jersey: Frank Sakamoto (presumed; abducted, then killed)
- McLean, Virginia: Daniel Carr, his driver, and his girlfriend (killed by Penny and Theo)
- McLean, Virginia: A security detail (stabbed once in the neck)
- Unspecified location in the woods: Three of Eliza's henchmen (All shot)
- New York City: one of Eliza's henchmen and two business partners (All shot)
- Hudson valley: Two FBI agents (one was strangled with rope until his neck snapped, the other was stabbed once in the head with an icepick)
- Unspecified location: FBI agent Alison Barton (non-fatally shot and used as bait before being taken to a remote location and fatally slitting her throat)
- New York City: Two FBI agents (both shot)
- Just like another student of Arthur Strauss, Joe Carroll, Theo is also a main antagonist during the series. Therefore are all the main antagonists at this point in anyway related to Joe Carroll to one point or another. (Joe Carroll has a direct connection with Arthur Strauss, who also has a direct connection with Theo. Arthur Strauss is the all ending connection between them all, not Joe Carroll.)
- Theo is the first Main Antagonist who killed another Main Antagonist (Arthur Strauss).
- Noble has shown through out his killings that he is well versed in Close Combat, Marksmanship, Manipulation, infiltrating high security cyber environments, breaking sophisticated encryption algorythms, removing Physical traces connecting him to the crime scene, disabiling CCTV's and other types of video cameras, masking his online IP to the point not even FBI can crack it, Knife Killing Techniques, masking his Physical Appearance and voice, and keeping hidden from law enforcement.
- Theo Noble claimed to Ryan Hardy in a phone conversation that he has killed hundreds of people, other than those seen murdered by him in the series.