Forget Harry Potter alone: Severus Snape is one of the most complicated characters written in history. It's no wonder he has such a massive fan following as well as plenty of Potterheads who can't stand him. He represents so much to so many: unrequited love, or the creepy guy who would never let you go. He's the teacher who bullied you and made school a nightmare as well as the life-risking traitor who saved the world through his double agent status. It's almost impossible to completely love or hate him, and really had Alan Rickman not portrayed Snape in the films, more people would have likely despised him, just as more fans would have written off Draco Malfoy without Tom Felton as the bully.
Snape has proven that he was worthy of Dumbledore's trust as often as he has proven Lily (Evans) Potter right about his cruel nature, as is evidenced in these Harry Potter: 10 Times Snape Was The Worst (10 Times He Was A Hero).
20 The Worst: He Bullied Harry Every Day
Many schools have a zero tolerance policy when it comes to bullying, but that's impossible to enforce when a teacher is the source. Severus Snape bullied the kids he didn't like every single day. Poor Harry was often the target of Snape's wrath, but Neville Longbottom was likely the most traumatized by Snape's sneering taunts.
19 A Hero: He Saved Harry From Quirrell's Spell
J.K. Rowling gave fans the biggest red herring and example of foreshadowing in the series when she made it seem as if Snape were cursing Harry Potter off his broom during a Quidditch match when Professor Quirrell was actually to blame. Snape saved Potter's life, as he did on multiple occasions.
18 The Worst: He Told Voldemort The Prophecy And Sold Out His Best Friend
Lily Evans may have been the only true friend Snape had in his life and he sold her out to Voldemort by sharing the prophecy he'd overheard. He'd spend the rest of his life making up for it, but had he listened to her in the first place, he wouldn't have had to.
17 A Hero: He Worked As A Double Agent For The Order Of The Phoenix
The most obviously heroic thing that Snape did was work as a double agent for the Order of the Phoenix, constantly putting his own life at risk. His skill with Occlumency and position as a remorseful Death Eater gave him the advantage he needed to pull it off, but it did cost him his life in the end.
16 The Worst: He's Mean To All The Students He Doesn't Like
Snape doesn't only pick on students in his own classroom who don't perform well or please him, but he even makes fun of students both in and out of the classroom like a common bully. He's even made fun of Hermione's appearance, which is pretty low, especially considering that he's had plenty of people do the same to him.
15 The Best: He Gave Harry Closure
Snape owed Harry nothing at the time of his demise. He'd given his life for the lives of Harry's parents at this point, even after protecting Harry for years. Still, he opted to give Harry closure, giving the boy his own memories of his mother and his feelings to explain everything to the teen after Nagini's attack.
14 The Worst: He Takes House Points For No Good Reason
We love to joke about how Dumbledore gives away House Cup points left and right, but he almost has to, given how many Snape is allowed to take away for no good reason. He even takes them away from Hermione Granger for answering questions correctly as an "insufferable know-it-all"!
13 The Best: He Made Wolfsbane For Remus
While it was certainly at Dumbledore's request, and he wasn't very kind while going about it, Snape did follow through and brew the wolfsbane potion that allowed Remus Lupin to work at Hogwarts, which also gave the students their first and really only training in Defense Against the Dark Arts they desperately needed in the years to come.
12 The Worst: He Revealed Remus' Secret
On the flip side, Snape also despised Lupin and surreptitiously worked to reveal his true nature as a werewolf to the students, such as the time he assigned his class homework about werewolves, knowing they would figure it out. Hermione Granger actually deciphered the clues, which likely annoyed Snape, but his loathing of Lupin was deeper than his disdain for Hermione.
11 The Best: He Befriended And Comforted Lily Potter
When Snape met Lily Evans as a little girl who didn't understand her own powers, he immediately befriended her. Even though he did this because she was a witch and obviously disliked muggles, and he likely had a crush on her from that moment on, it still spoke of a good, or at least conflicted, heart, since he was drawn to such a good person and went out of his way to help her.
10 The Worst: He Called Lily A Mudblood When She Defended Him
Snape's adoration of Lily made it even worse when he called her a mudblood, the worst slur you can call a muggle-born witch or wizard, when she tried to defend him against James Potter and his friends when they bullied him. It was a terrible thing to say to anyone, let alone one's best friend.
9 The Best: He Gave Up His Life For The Order
Snape didn't just work as a double agent for the Order of the Phoenix. He literally gave his life up, knowing it could be ended at any moment, knowing he'd have to work as a teacher at Hogwarts, a job that he seemed to loathe. He had no life outside of these duties and looked at it as atonement for his role in the loss of Lily.
8 The Worst: He's An Unfair Teacher
Why Dumbledore hires the worst teachers remains a baffling question, but Snape truly is one of the most terrible, unfair instructors in the school. He's terribly hard on anyone who isn't in Slytherin, particularly on students he doesn't like, and even punishes those who do well. He's also hard on students who are obviously trying their best, and seems to take joy in destroying any potions that don't work well and awarding zero points.
7 The Best: He Thwarted Umbridge And Refused To Use Truth Serum
With Dumbledore gone from Hogwarts, Snape had the freedom to side with evil, in this case, Dolores Umbridge, if he wanted to do so. Instead, he thwarted Umbridge and proved his loyalty again, lying about having any Veritaserum, AKA truth serum, to protect the students at Hogwarts (as well as himself).
6 The Worst: Tried To Off Sirius And Remus With Dementors
Snape wasn't only protecting the kids from a werewolf and a fugitive when he suggested the Dementors perform kisses on both Sirius Black and Remus Lupin in Prisoner of Azkaban. He had revenge on the brain and was downright gleeful when he posed the threat aloud to his old enemies.
5 The Best: He Gives Up His Life Again In Cursed Child
In Harry Potter and the Cursed child, Snape learns of his fate after working as a double agent. Knowing that he will lose his life if he helps restore the world to order, he does so anyway, proving that he's always cared more about the greater good than his own life.
4 The Worst: He Refused To Hurt Harry
While fleeing after taking out Dumbledore, Snape gave himself away by refusing to harm Harry while the boy angrily flung curses at him. It would have only taken a second to knock him out, deflect suspicion from himself and even give Harry a moment's peace after the terrible ordeal.
3 The Best: He Led Harry To The Sword Of Gryffindor
Harry and his friends were wandering around the woods, completely unaware of what to do next with Dumbledore gone, and may not have gotten any farther without Snape's help. He sent his Patronus to alert Harry where the Sword of Gryffindor could be found and helped destroy the locket Horcrux.
2 The Worst: He Didn't Continue Occlumency With Harry
Snape knew very well how much the fate of the world depended on Harry Potter learning Occlumency so the Boy Who Lived could shield his mind from You-Know-Who, yet his own pride and inability to handle a snarky teenager got in the way and he stopped giving him lessons.
1 The Best: He Took Out Dumbledore To Protect Draco On Dumbledore's Orders
One of the most difficult duties that Snape ever had to fulfill was his promise to both Narcissa Malfoy and Albus Dumbledore, which he did when he cast the Killing Curse on the Headmaster. Harry saw it as an act of evil, but Dumbledore, who was already perishing, took Snape's secret to his grave.