Despite his incredible powers, the various versions of the Hulk, each with its own dark personality and anger issues. Samson doesn't have the same problem, but he did start out with an issue of his own.
Gamma rays are generally one of the worst ways to gain super powers in the Marvel Universe. While victims of gamma accidents generally end up incredibly strong (or superhumanly smart, in the case of the Leader), the mutations also tend to leave them with freakish appearances. Even Jennifer Walters (aka She-Hulk), who tends towards a less exaggerated physique than her cousin Bruce, still ended up with green skin, occasional anger issues, and a body that morphs into more monstrous forms under the right conditions.
On the other hand, there is one member of the Hulk family who gained possibly the best version of gamma powers from the beginning, and managed to keep a fairly stable control of them throughout most of his career: Doc Samson. Despite this, the psychiatrist superhero does have a notable weakness; one that can be traced all the way back to his biblical namesake. And while this weakness once appeared to have been eradicated, recent developments have shown that it's returned in some surprising ways.
Doc Samson's Origin
Introduced in The Incredible Hulk #141, Doctor Leonard "Len" Skivorski Jr. was a psychiatrist recruited by the military to help in an experiment to siphon off the gamma radiation from the Hulk and revert him (possibly permanently) into Bruce Banner. The experiment worked and the Cathexis-Ray Samson had helped design was even able to use some of the energy to revive Banner’s girlfriend Betty Ross, who had been transformed into a being of living crystal. Both Betty and Bruce became human, ending the saga of the Hulk… or so it seemed.
Shortly after the experiment, Skivorski (who had been going by the name "Doctor Samson" after his long-haired father’s nickname) realized that the Cathexis-Ray still contained a significant amount of the Hulk’s energy. Curious as to what the effects of a controlled burst of gamma rays might do to him - and wanting to be viewed as more of a man by the public - Skivorski secretly exposed himself to the radiation. The experiment transformed the formerly brown-haired scientist into a superhumanly strong, muscle-bound man with long green hair.
The new "Doc Samson" also retained his full intellect, although his inhibitions were now much lower; not unlike Jennifer Walters when she transforms into the gamma-powered She-Hulk. Since gamma rays in the Marvel Universe transform people into the versions of themselves that they keep hidden from the world, it’s possible the gamma rays transformed Leonard Skivorski into what he saw as his ideal self: powerful, confident, and a total ladies’ man.
Leonard even started flirting with Betty Ross, which proved disastrous when a jealous Bruce Banner re-exposed himself to gamma rays and turned back into the Hulk. Doc Samson actually had to fight the Hulk, but learned that while he possessed the power of a calm Hulk, the real Hulk could grow stronger when he got angrier, allowing him to easily beat up Doc Samson. In the aftermath, Samson continued working with the military but still felt guilty about his role in bringing the true Hulk back into being.
Samson's gamma weakness
In The Incredible Hulk #143, shortly after the fight, Doc Samson discovered something unusual about different Hulk forms various weaknesses and powers, from varying levels of intelligence to the extent of their potential rage and strength.
Doc Samson’s weird vulnerability, which would mean a villain could negate his powers by shaving his head, was eventually forgotten by later comic creators, who depicted him with very short hair but no appreciable loss in strength. Behind the scenes, it's possible writers forgot this limitation, or chose to ignore it thanks to its fairly ridiculous nature. Despite this, it's possible to reconcile the change with Marvel canon - gamma powers are heavily tied to mental states, and Samson is an excellent psychiatrist, and has learned to control his powers in ways others haven't (for example, when he weaponized his gamma-fueled rage to take down a psychic in Warren Ellis and Mike Deodato's Thunderbolts.) But whether forgotten or overcome, Samson's odd relationship with his hair would return in an unexpected way.
Samson's evil hair
After years of being the Hulk’s ally, psychiatrist, and occasional sparring partner, Samson developed a case of multiple personality disorder himself in The Incredible Hulk #600. This causes the good doctor to manifest an "evil" persona known as just "Samson." Whenever Samson takes over, Leonard’s gamma-infused physique grows bigger and his green hair grows out, apparently now an indicator, rather than the controlling force, of his increased strength. Samson apparently killed his other personas but later sacrificed himself to save Bruce by absorbing excess energy from an overloading Cathexis Ray Generator.
Of course, comics being comics, Samson doesn’t stay dead for long. He briefly returns during the 'new Hulk hero Doc Sasquatch, Doc Samson is actually hairier and more bestial than he’s ever been, showing that even when he doesn’t have his ludicrous weakness, his relationship with his hair is destined to stay complicated.
