Heroes have an Evil Side

"Joseph "Robbie" Robertson:(seeing Spider-Man in black suit's photos) Black-suit Spider-Man! Peter, these are incredible! We gotta have these. I'll pay you the usual rate. Peter Parker: If you want the shots, I'll take the staff job. Double the money."

- Peter (still wearing the black costume) talk back to Jameson by giving him some respect

In various settings and as the story progresses, perhaps due to often fought in many battles, exposure to evil influence, freak accidents (magical, technological, or both), traumatic past, or even dark secrets surrounding his/her origin, a hero revealed to had an Evil Side, inner darkness composed of the said hero's worst aspect in his/her psyche within his/her subconscious.

Overview
All good guys, even the one with pure heart, had darkness within their psyche. Many of them yet to realizing it until circumstances that related to it occured where for the first time in his/her life, monstrous beings composed of worst aspect of his/her psyche, comes to the surface in form of a violent, if not truly evil secondary personality of the said hero/heroine when he/she was in the grave danger or having certain freak accident that brough the worst aspect of his/her psyche to life. Medical term of a person who had two personality, one is typical good personality and the other is the hero's own malevolent side brought to life in form of vicious personality aka. Evil Side is Split Personality Disorder.

While having an Evil Side is bad, it would be a serious problem had whenever a hero/heroine had his/her evil side took over, the hero/heroine proved to be more powerful, competent, and deadly than he/she usually capable of. Depend on the plot, had the hero/heroine had his/her evil side take over, they had certain symptoms from having glowing eyes to suffer additional deformation that gave him/her intimidating appearance. Not only that, the hero/heroine's Evil Side may constantly argued with the hero/heroine's own psyche about things when his/her friends/family/loved ones not around, which usually happened when the hero/heroine aware with his/her Evil Side's presence within him/her. Since his/her Evil Side still part of his/her psyche, the hero/heroine had to cope and accept his/her inner darkness that might not only made his/her Evil Side become cooperative with him/her, but also merges with her real personality that made him/her sane. Even so, the hero/heroine must realizing that they need to deal his/her evil side with one way or another due to possible danger that his/her evil side pose to everyone around her.

Examples

 * Dr. Jeckyll: Dr. Jeckyll had an experiment that involving this, and tried to brought his inner demons to life with a serum. Unfortunately, his inner demon, Mr. Hyde, proved to be more dangerous that he must deal it with one way or another.
 * Midnight Sparkle: Twilight Sparkle aka. Sci-Twi revealed to had Evil Side in form of Midnight Sparkle brought to life by her freak accident with magic.
 * Spider-Man: Tobey Maguire's incarnation of Peter Parker aka. Spider-Man had his evil side brought to life by his black suit that actually disguised form of symbiote called Venom.
 * Mal: Mike is known to suffer Multiple Personality Disorder, and thus his Evil Side is conformed to be his Evil personality.

Gallery
NOTE: The limit is for 20 pictures only