Albus Percival Wulfric Brian Dumbledore; Order of Merlin First Class, Grand Sorcerer, Supreme Mugwump (head of the International Confederation of Wizards), Chief Warlock of the Wizengamot, advisor to the Minister of Magic. He is most famous for his defeat of Gellert Grindelwald, who is considered to be the second most dangerous Dark Wizard of all time- second only to Tom Riddle, the discovery of the twelve uses of dragons blood and his work on alchemy with Nicolas Flamel.
Through his resistance to the rise of Lord Voldemort he founded and led both the first and second Order of the Phoenix and is considered to be one of the Lightest Wizards of all time. But what do people not know about Albus Dumbledore?
One may see the "Harry Potter" series as the adventures of the Golden Trio as they save the wizarding world from the evil Lord Voldemort, but here is how some fans choose to view the series. "Harry Potter and the Sorcerer's Stone" or Albus Dumbledore and that time he hid something that Voldemort wanted in his school and defended it with protections so weak that three eleven-year-olds could get through them.
"Harry Potter and the Chamber of Secrets" or Albus Dumbledore and that time he didn't shut down the school when a giant snake was wandering around petrifying students. "Harry Potter and the Prisoner of Azkaban" or Albus Dumbledore and that one time he sent two traumatized teenagers back in time rather than saying "Hey, maybe I should get this guy a trial." "Harry Potter and the Goblet of Fire" or Albus Dumbledore and that one time he didn't figure out that a member of his faculty was a death eater in disguise. "Harry Potter and the Order of the Phoenix" or Albus Dumbledore and the exact wrong way to handle a teenager who has post-traumatic stress disorder.
"Harry Potter and the Half-Blood Prince" or Albus Dumbledore and the point at which you should realize that keeping secrets is unhealthy. "Harry Potter and the Deathly Hallows" or Albus Dumbledore and the year that he continued to screw everyone over from beyond the grave.
Now, you may be thinking, "So, the guy may not be the best judge of a situation or character but is he really all that bad?" But here are some examples of how he manipulated people and situations surrounding him:
He used Lily to manipulate Snape: When Snape asked Dumbledore for his help to save Lily he coldly replied, "and what will you give me in return Snape?" which led to Snape saying "Anything" making him a servant to Dumbledore. When Lily died, Dumbledore used her to manipulate Snape once again to make him protect Harry. "Her son lives. He has her eyes. You remember the shape and color of Lily Evans eyes I'm sure?...You know how and why she died. Make sure it's not in vain. Help me protect Lily's son."
He used Harry to manipulate Slughorn: Not only did he use Harry to get Slughorn to return to Hogwarts, he also tried to turn Harry into a manipulator so that he could get the memory of Tom Riddle asking about Horcruxes, even though he already knew the information.
He was never completely honest with Harry: This is especially true in "Order of the Phoenix." In many people's opinion, Dumbledore is partially at fault for Sirius' death. He never told Harry the importance of learning Occulumency and made Snape, the worst possible person imaginable, teach him which inevitably ended in disaster. He didn't tell Harry about the prophecy until he absolutely had to and he never told Harry that he would have to die, leaving the dirty work to Snape. He groomed that poor boy into someone who would willingly die "for the greater good."
He left Harry with the Dursleys: He left baby Harry on the doorstep of Number Four Privet Drive in the middle of the night with only a blanket and a note. He never checked in on Harry to make sure that he was being taken care of, which he wasn't, and forced the Dursleys to keep Harry even though they hated him and were terrified of magic.
What stands out the most is what happened to Sirius Black: The Fidelius Charm is an extremely difficult, multifaceted and potent charm that can be used to conceal a secret inside an individual's soul. This charm was used to protect James, Lily and Harry Potter from Lord Voldemort at their home in Godric's Hollow, the location of which was the secret entrusted. They designated their Secret-Keeper as Sirius Black but then switched to Peter Pettigrew at the last minute as they thought that he would be less obvious.
The only people who knew of the switch were the Potter's, Sirius Black, Peter Pettigrew, and Albus Dumbledore who was the one to cast the spell. When Peter betrayed them to Voldemort and the Potter's consequently got killed, Sirius went after Peter. This ended with Peter faking his death and Sirius being thrown into Azkaban, the wizarding prison, without receiving a trial. Dumbledore, who knew enough of what happened did nothing to help him. The man who was an advisor to the Minister of Magic did not lift a finger and left Sirius to rot in Azkaban until he was finally able to break himself out twelve years later. And after that Dumbledore didn't do anything to help him achieve his freedom, instead he locked Sirius in his childhood home where he was abused and used him so that his precious Order would have somewhere to meet, which was a factor that helped lead to Sirius' death.
All in all, when you really look at the story as a whole you can see that Dumbledore is a master manipulator who would do anything "for the greater good." He is a man who was so afraid of letting another dark wizard come to power that he channeled his own darkness into training a human weapon from childhood to fight the darkness that he knew he couldn't all while pretending to be the wise wizard mentor he wished he actually was.