One of the main components of the Harry Potter series is, obviously, magic. Without magic, it wouldn't be much of a story, now, would it? The wizarding world boasts a vast lexicon of various spells, curses, charms, and more to use on a daily basis, whether for menial household tasks or more serious instances of dueling and fighting against others.
We see a great deal of different kinds of magic in the books and films. Of course, we all know that the three Unforgivable Curses are the worst of all magic, but there are quite a few other deadly spells and incantations out there that should really be unforgivable themselves. Let's take a look at some of the (other) worst spells known to wizardkind.
This deadly spell is cast by Harry in the sixth installment of the series. He learns the spell from his Potions book, which has been edited by the Half-Blood Prince. Harry foolishly performs the spell without knowing what it does while in the midst of a conflict with his enemy, Draco Malfoy.
The curse slices his body open and causes a great pool of blood to flow on the floor. It was possible Malfoy could have died had Snape not arrived and recognized the curse. He was able to heal Draco.
9 Snake Summons Spell
We only see the Snake Summons Spell used once in the series, during Harry Potter and the Chamber of Secrets. The spell is part Transfiguration as it allows Draco Malfoy to cast a serpent from his wand by using the incantation "Serpensortia." He uses it during his duel with Harry at the Duelling Club.
Snape tells Draco what to do, while Harry is left with the bumbling fool that is Gilderoy Lockhart. Lockhart tries to get rid of the snake, but only angers it. Eventually, Harry makes it calm down by speaking Parseltongue, which kick-starts the rumor that he could be the Heir of Slytherin.
8 Protego Diabolica
This powerful incantation was seen used by Gellert Grindelwald in Fantastic Beasts: The Crimes of Grindelwald. When cast, Protego Diabolica creates a massive ring of fire around the caster.
Any of their enemies that come in contact with it will be incinerated, but their allies can pass through the flames unharmed. Grindelwald uses the spell as a way to measure the loyalty of his supposed followers. The fire cast is similar to Fiendfyre, in that it can take on the form of monstrous creatures made of flame.
7 Expulso Curse
Expulso does what the name implies: it's an explosive curse that blasts things apart with a bunch of blue light billowing out when enacted. While we know it can throw people into walls, there is a disturbing implication that this curse could blast human beings apart.
We don't see it used in that way in the series. We see it used a few times though, such as in Harry Potter and the Deathly Hallows, when the Death Eater known as Rowle uses it on the table Harry, Ron, and Hermione were sitting at when they first leave the wedding at the Burrow.
Legilimens is the spell used during Legilimency, which is when someone peers into someone else's mind and can dig through their memories and emotions. The most skilled Legilimens are even able to imprint their own memories inside someone else's head if they wish to.
Harry is constantly under threat of this from Lord Voldemort, when he realizes they share a connection. This is the main reason Sirius wound up dying, due to Voldemort tampering with Harry's head. The only true defense against Legilimency is Occulemency, which is the study of how to close your mind off to prying forces from the outside.
Confringo is another version of the blasting curse, but it is considered dark magic and likely more powerful than Expulso. This was used by both Harry and Hermione in Deathly Hallows. Harry cast this curse while he was flying in Hagrid's motorbike and they were attacked by Death Eaters.
He separated his sidecar from Hagrid to free himself and try to get out of the situation. The other time it was used was in Godric's Hollow, when Hermione needed to get herself and Harry out of Bathilda Bagshot's home. An accident with the powerful spell saw Harry's wand destroyed.
Reducto is also a curse that can cause things to be blasted, but it isn't quite as intense as Confringo or Expulso. It is used more as a way to just move something seemingly unmovable out of one's path.
Harry uses this spell quite a few times during the third task of the Triwizard Tournament, in Harry Potter and the Goblet of Fire. While he's inside of the giant hedge maze, it becomes a helpful way for him to get strange entities and obstacles out of his way. Harry also teaches the spell to the D.A.
3 Memory Charms
The memory charm we see used in the series uses the incantation "Obliviate." It can wipe one's memory completely, or just erase specific encounters. The worst example of this occurs in the second book of the series, when Gilderoy Lockhart tries to wipe Harry and Ron's memories.
Sadly for him, he uses Ron's damaged wand; he winds up wiping his own memory completely and even winds up in St. Mungo's to try and recover. Wizards also frequently use this spell on Muggles who get too curious for their own good. You can see how it could be extremely dangerous, though, when used by the wrong people.
2 Full Body-Bind
The Full Body-Bind is an absolutely terrifying bit of dark magic that Hermione Granger actually masters in her first year at Hogwarts. The spell is cast with the incantation "Petrificus Totalus" and it leaves the victim completely unable to move, with their arms and legs locked together by their sides.
Poor Neville Longbottom winds up on the wrong end of Hermione's wand when he tries to stop the trio from going out after dark, in an attempt to keep Gryffindor from losing more points. It is used later in the series too, such as during the battle at the Department of Mysteries, cast by Harry Potter on Dolohov. It's used for a bit of comic relief in the series, really, but the implications of this spell just don't bear thinking about.
To put into perspective just how powerful and deadly Fiendfyre is, it is one of the few things in the world that has the ability to destroy a Horcrux. It is a type of cursed fire that consumes everything in its vicinity and twists into terrifying creatures.
Crabbe stupidly casts it in the Room of Requirement, when he, Goyle, and Malfoy try to stop Harry from getting the Ravenclaw's Diadem. Ultimately, it's destroyed in the flames and Crabbe dies in the fire too. These roles are swapped around in the movie, with Blaise Zabini appearing in the scene in Crabbe's place, while Goyle casts the spell and perishes in the flames.