Well-Intentioned Extremist/Playing With

Basic Trope: A character uses wholesome ends to justify their villainous deeds.
 * Straight: Bob seeks to maintain order in society...by installing a totalitarian dictatorship in which he is the sole ruler.
 * Exaggerated: Bob seeks to find the meaning of Life, The Universe, and Everything by mass murder, torture and genocide.
 * Up to Eleven: Bob seeks to eliminate human suffering and bring the humanity a paradise... by turning all living beings into orange juice and forcefully merging their souls.
 * Justified: Bob is deluded.
 * He actually has a point after all.
 * Inverted: Selfish Good
 * Subverted: Bob lied about his intentions.
 * Bob is revealed to be not that extreme
 * Double Subverted: Bob claims to have lied about his intentions, because the greater good involves him seeming like "the bad guy".
 * That was a lie.
 * Parodied: Bob wishes to save the world...by ripping the tags off of every mattress in the world.
 * Deconstructed: Despite his good intentions, many people turn on Bob for his actions.
 * In the end, Bob goes down in history as a Complete Monster of a ruler.
 * After being defeated by Alice, Bob realises all the sacrifices he made were for nothing because his plan failed, and has a Villainous BSOD as he reflects on what he's done.
 * Bob's extremism ends up causing the exact thing he wished to avoid.
 * Reconstructed: Bob is OK with the world hating him, so long as the world he creates is a better one in the end.
 * Zig Zagged: Depending on the writer, Bob's motive for his tyranny ranges from simple lust for power to desire to create an orderly society.
 * Averted: Bob is a Card Carrying Villain.
 * Bob is a Knight Templar who only thinks that his goal is good.
 * Enforced: "If we want our show to have more depth, we should give our 'villains' an understandable motivation and at least partially sympathetic goals."
 * Lampshaded: "I killed millions...to save billions!"
 * Invoked: Shoot the Dog
 * Exploited: Turns out, Alice is a Complete Monster, and is using Bob's Well Intentioned Extremist tendencies and (Anti-) Heroic Zeal to make it easier for her to Kill Em All.
 * Defied: "There are instances in which the means are too rotten to be justified by any ends."
 * Discussed: I Did What I Had to Do
 * Conversed: ???

Should you not go back to Well Intentioned Extremist, the world will no doubt suffer for it...and I shall see to it that you will not live to see such a tragedy take place.