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The Chief (choleric), Elasti-Girl (melancholic), Negative Man (phlegmatic), and Robotman (sanguine).
Alternatively, in the second incarnation: Celsius (choleric), Negative Woman (melancholic), and Tempest (phlegmatic).
Fantastic Four: Johnny (sanguine), Ben (choleric), Reed (melancholic), and Sue (phlegmatic) and later Franklin (leukine).
Although the first two are more obvious than the latter, and even the first two are more complex characters. Johnny has behaved cholerically on occasion (e. g. in the early issue where he left the team because he felt unappreciated) and Ben is often melancholy and introvert, e. g. going to a bar to try and drown his sorrows (after all, you could say that usually he wants to be left alone and then Johnny plays a prank on him). Also note that the Fantastic Four are also a four-elements example in a way that does not align with the descriptions above: Johnny is Fire, Ben is Earth, Sue is Air, and Reed is Water.
Hal Jordan is the cocky ace pilot who loves adventure (sanguine), Guy Gardner is the brazen tough guy who speaks his mind (choleric), Kyle Rayner is the quiet artist who likes to work alone (melancholic), and John Stewart is the born leader who stays calm under pressure (phlegmatic).
In some interpretations, Guy Gardner is sanguine (the laid-back bruiser who cracks wise at danger), John Stewart is choleric (the hard-nosed military man who leads every charge), Hal Jordan is melancholic (the veteran adventurer battling personal demons), and Kyle Rayner is phlegmatic (the calm, intuitive artist).
Brazilian comic Monica's Gang: Monica is choleric (and how!); Casc„o/Smudge is melancholic; Magali/Maggy is phlegmatic; and Cebolinha/Jimmy Five is sanguine.
Reign of the Supermen begins with four characters each claiming to be either Superman risen from the dead, or a replacement for the character and each is referred to by one of Supes' old nicknames. Eradicator as the Last Son of Krypton (choleric); the Man of Tomorrow (Cyborg Superman) is fairly melancholic (well, appears to be); murdering villains left and right, the Man of Steel (Steel) is basically phlegmatic; and The Metropolis Kid (Superboy) is, of course, sanguine cranked Up to Eleven.
The Robins: Dick Grayson (sanguine), Damian Wayne (choleric), Jason Todd (melancholic), and Tim Drake (phlegmatic).
Also the Batgirls: Barbara Gordon (phlegmatic), Helena Bertinelli (choleric), Cassandra Cain (melancholic), and Stephanie Brown (sanguine).
Scott Pilgrim: Envy/Stacey (choleric), Stephen/Kim (melancholic), Young Neil (phlegmatic), and Scott/Knives/Ramona (sanguine).
In the early "Spider-Man" comics of the Romita era, we had Peter Parker (melancholic), Harry Osborn and Flash Thompson (choleric), Gwen Stacy (phlegmatic) and Mary Jane Watson (oh so very sanguine).
Teenage Mutant Ninja Turtles: Ill-tempered and pessimistic Raph (choleric), loyal and martyr-like Leonardo (melancholic), rational and calm Don (phlegmatic), and easy-going and lively Mikey (sanguine). There's some tension between Leo, who expects his brothers to do what he tells them, and Raph, who's too insular and stubborn to follow without challenge.
Watchmen: Comedian (choleric), Rorschach (melancholic), Dr. Manhattan (phlegmatic), Ozymandias (sanguine), and Laurie and Dan (leukine).
The original five X-Men: Scott Summers (melancholic), Bobby Drake (sanguine), Warren Worthington III (choleric), Hank McCoy (phlegmatic) and Jean Grey (leukine).