Clark Thomas Edison is one of the many squinterns that Dr. Brennan has at the Jeffersonian. He is portrayed by Eugene Byrd.
Clark Edison is a doctor who was hired by the Jeffersonian following Zack Addy's departure to Iraq (The Widow's Son in the Windshield). However, his position with the team was short lived when Zack returned later in the episode to retake his position in the lab.
Clark returns in the episode The Verdict in the Story, where he is the scientific counsel for the defense in the murder trial of Dr. Brennan's father, Max Keenan. Clark goes over the evidence against Max meticulously and discovers that the murder weapon is not the one Zack declared it to be, thus causing doubt that Max had indeed murdered FBI Deputy Director Kirby. The defense's advantage was short-lived, however, as the actual murder weapon was shortly discovered in Brennan's home.
After Zack's departure at the end of Season 3, Clark appears in several episodes of Season 4. However, Clark finds it hard to work in the lab, claiming that there was too much interpersonal drama, though he later returns. During Season 6, he lightens up considerably, in part because of his girlfriend's urging him, shares more of his personal life and takes an interest in those of his coworkers.
Clark returns to the Jeffersonian in the Season 6 episode The Couple in the Cave after being passed over for a promotion at his job in Chicago. Later in that same season, in The Body in the Bag, viewers learned that Clark held a summer job at the National Security Agency, though he refuses to discuss any details of it.
In Season 8 we learn that he took the position of the absent Dr. Brennan, much to the dismay of Angela. He did implement some new methods which were not well appreciated, but a returning Dr. Brennan, who worked in the lab in secret, remarked that they were really efficient. It becomes obvious that Clark is not very happy with the prospect of Dr. Brennan's return, but he is not working against it. When she eventually returns he seems to be happy but at the same time sad, that he would lose his position in the Jeffersonian. At that time Cam announced that the Jeffersonian was actually in need of two anthropologists, one for the crimes and one to do some serious archeological work. Clark happily accepts the latter position since Dr. Brennan announces that she loves crime, while he exclaims that he loves archeology.