Ivanova (the Cynic); Sheridan (the Optimist); Garibaldi (the Realist); Franklin (the Conflicted), and Marcus (the Apathetic).
Alternatively, Franklin could be seen as a second Optimist, since he has some of the stubborn and optimistic traits, but is not as determined or decisive as Sheridan. Ivanova and and Garibaldi also sometimes share both the Cynic and Realist roles.
Ivanova insists that she's a Realist, but even she admits that's because she's Russian.
Blackadder Goes Fourth featured Cpt Blackadder as the cynic and occasional (not to say, sole) realist, airheaded Lt George as the optimist, the scheming Cpt Darling as the perpetual cynic, and fellow Cloud Cuckoo Landers General Melchett and Private Baldrick taking turns serving as the Apahetic.
Buffy the Vampire Slayer: The core Scoobies consisted of Giles (Cynic), Buffy (Realist), Xander (Apathetic), and Willow (Optimist).
Other temporary Scoobies included Cordelia (Cynic), Angel (The Conflicted), Spike (either Apathetic or Cynic), Anya (Cynic), Riley (Optimist), Tara (Realist), and Faith (The Conflicted).
Angelus' old group consisted of Angelus (Realist), Spike (Optimist), Drusilla (Apathetic), and Darla (Cynic).
Charmed: Although Prue and Paige never appeared together, the Charmed ones all qualify. Prue (the Realist), Piper (the Cynic), Phoebe (the Optimist), and Paige (the Apathetic).
"Series/Znation": Garnett was the Optimist, Roberta is the Realist, Mack is the Pessimist, and Doc was Apathetic.
Optimist: David Lister, always hopeful in the crew's plans, almost to the point of blind hope in the absence of no logical certainty that the plan will run smoothly. Will be the first one to support looting a spaceship on the verge of exploding, just so he could get a supply of curry.
Cynic: Arnold Rimmer. He'll pretty much say no to any plan, percieving it to be too risky. Has practically no faith in anything.
Realist: Probably Kryten. He'll acknowledge that Lister is being overly optimistic, and that his plan probably is suicidal, but yet informs Rimmer that even though a mission might be dangerous, they are in danger (of possible low food supplies) and must take the chance to survive anyway.
Conflicted: The Cat. While he will usually side with Rimmer's cowardly and self-serving plans, he will sometimes back up Lister's dnagerous and insane ideas on the account that he hates Rimmer.
Apathetic: This role is fufilled by Holly in earlier episodes, and Kochanski in later, as they will usually stand in the background while above four bicker and occasionally put in their own plans.
Star Trek: Voyager: While there are obviously more than four or five characters, the overlapped roles have characters that fall under different aspects of each role. For example, Tuvok is the coldly-logical Cynic, Paris is the street smart Cynic and Torres embodies raw hostility.