James T. Kirk, alleged opportunist
An opportunist was someone who took advantage of circumstances rather than being guided by consistent values.
According to Chang, James T. Kirk was "an insubordinate, unprincipled, career-minded opportunist with a history of violating the chain of command whenever it suited him." (Star Trek VI: The Undiscovered Country)
In 2370, Kira Nerys described the provisional government of Bajor as consisting of political opportunists who were consumed with infighting rather than the good of their people. (DS9: "The Homecoming")
In 2373, Tekeny Ghemor described Glinn Borven as "a political opportunist with all the loyalty of a hungry vole". (DS9: "Ties of Blood and Water")
In 2374, Kira told Gul Dukat he was "an opportunistic, power hungry dictator". (DS9: "Sons and Daughters")
In 2377, Tuvok believed that while in The Void, USS Voyager's crew would have to be opportunistic to survive. Kathryn Janeway disagreed. (VOY: "The Void")