Super-Powered Evil Side/Playing With

Basic Trope: The Hero has a darker, more powerful, alternate personality.
 * Straight: Bob transforms into his evil other half Dark Bob when he is in trouble.
 * Exaggerated: Bob is the most kindhearted human to ever live albeit not that good a fighter. Dark Bob is a literal Complete Monster, but he's also much stronger.
 * Justified: Bob has a split personality disorder. His evil side isn't objectively more powerful, but is much more ruthless and ambitious, so he is able to accomplish more in some situations.
 * Inverted: Bob is the evil half, Dark Bob is the good half.
 * Alternatively, Emperor Evulz has a Superpowered Good Side.
 * Subverted: Dark Bob doesn't really exist, Bob only pretends to be him to throw off his foes.
 * Dark Bob seems to be evil at first, but he's actually a nice guy.
 * Bob's evil side turns out to be weaker than Bob himself.
 * Double Subverted: Dark Bob does exist, but Bob has only ever pretended to be him... until now.
 * ...but was only being good because Bob was suppressing him. Dark Bob really is unstable.
 * Parodied: Bob grows a mustache when he becomes Dark Bob. Dark Bob is fond of twirling his mustache evilly.
 * The worst thing Dark Bob does is literally steal candy from a baby.
 * Deconstructed: Bob is avoided by everyone because he could turn into Dark Bob with no warning. Dark Bob is something of a joke among supervillains because he could turn into Bob at the wrong moment. Both of them are depressed as a result.
 * Bob is terrified of becoming Dark Bob and avoids people as a result, not wanting to hurt them.
 * Reconstructed: Bob is determined to make the best of it and Dark Bob won't let a puny mortal hold him back.
 * Zig Zagged: Bob has several personalities. There's Dark Bob and Bobby, the evil ones, and there's Rob and Robby, the good ones. Then there's Roberta...
 * Averted: Bob has no evil personality.
 * Enforced: Bob's actor wants to show more dramatic range.
 * Lampshaded: "Bob is not here right now."
 * "There is no Bob... only Zool, er, Dark Bob..."
 * Invoked: Bob is superpowered in his own right; he shows his 'evil' side to gain credibility with a villainous group he means to infiltrate.
 * Exploited: Bob's Treacherous Advisor gives him a superpowered evil side as a Xanatos Gambit: if he uses it he will turn evil and thus become Emperor Evulz's henchman. If he doesn't use it, he dies and can no longer interfere with Evulz's plans.
 * Defied: "Wait, so you're saying that I have a Super Mode... but it's evil? Screw that! I'll take my principles over power any day!"
 * Discussed: I'll do whatever it takes to save the world, even if it means losing myself to The Dark Side."
 * Conversed: "Why is it that if a normal human gains superpowers, his personality always gets darker when they're in use?"