Marilyn Stark is a central antagonist in the seaQuest episode "To Be Or Not To Be." She is portrayed as a highly competent and strategic individual, but her actions are ultimately motivated by a deep-seated resentment and a desire for revenge.
As a former Captain of the seaQuest, Stark was once in a position of authority. The sources do not explicitly state who relieved her of command, but it can be inferred that it was likely someone within the United Earth/Oceans Organization given her subsequent antagonism towards the organization. Described as being in her 40s, she is depicted as a strong, intense, and charismatic leader. Her sharp intellect and strategic capabilities are evident in the meticulous planning and execution of the attack on the Gedrick Power Station. The loyalty of her crew on the renegade sub suggests that Stark is a persuasive figure who has provided them with a sense of purpose. It is noted that Stark was previously stationed at the Livingston Trench and it is implied she has a past connection with the United Earth/Oceans Organization.
In "To Be Or Not To Be," Stark commands a renegade Typhoon-class submarine, which carries out attacks on mining outposts and the Gedrick Power Station. She is directly responsible for these attacks, which cause substantial damage to both the power station and the seaQuest. Furthermore, it is revealed that Stark is the saboteur who implanted a virus into the seaQuest's systems. Her attacks seem to be a deliberate attempt to destroy her former command and establish control over the seas. During the attacks, Stark displays a ruthless nature, willingly endangering her crew and threatening insubordination. However, she also demonstrates moments of intense focus and determination, particularly when engaged in combat. Her ultimate goal is to dismantle the established order and take over the seas, revealing her ambitious and power-seeking nature. Her crew's devotion highlights her charismatic yet dangerous leadership style.
Stark's motivations are rooted in a desire for revenge and a rejection of the U.E.O.’s authority. She seems to operate under the belief that the ends justify the means, showing a willingness to sacrifice others for her goals. Stark harbors resentment towards the perceived weaknesses of the current order and is determined to create a new one. She regards the crew of the seaQuest as "tourists" who lack the understanding of her methods and vision.
As an adversary, Stark directly challenges the authority of Nathan Bridger when he assumes command of the seaQuest. She sees Bridger as an obstacle to her goals and shows a blatant disregard for his authority. She also has a significant interaction with Maxwell, the former Sensor Chief of the seaQuest, who now serves as her sensor chief on the renegade sub. She displays distrust of the U.E.O. and anyone associated with the organization. It is later revealed that she was Bridger's sponsor when she applied for her officer's bars, indicating that he likely had a role in her early training and career advancement, as sponsors typically mentor and guide those they sponsor. Additionally, Stark believes that Bridger is after the seaQuest because she believes if she can't have it, the "rebels own the sea."