Listen. A lot of people really love "Harry Potter" and people really love to talk about Harry's great characteristics and Neville's glow-up. Yeah, these guys are great, but there are so many characters that don't get the appreciation that they deserve.
1. Bill Weasley
Bill Weasley is a GOD. He was a Prefect, Head Boy, and he worked for Gringotts. Not to mention, he's also a member of the Order of the Phoenix that risked his life on multiple occasions and helped out so much during the Second Wizarding War, offering Harry & company a place to stay and fighting in the Battle of Hogwarts.
2. Nymphadora Tonks
Tonks was always there when she was needed, from when she escorted Harry to Grimmauld Place to when she went to help fight the Death Eaters in the Department of Mysteries. She sacrificed a lot to fight Voldemort and his army during the Battle of Hogwarts, and her death was one of the saddest ones of the series. Oh, and don't call her Nymphadora.
3. Luna Lovegood
Harry took Luna for granted as long as he knew her. No one (except maybe Ginny and Neville) really appreciated her and what she did for Dumbledore's Army and for the Order. She was willing to fight from the first moment we met her and her bravery had no end. Even after she got kidnapped by snatchers, she couldn't stay in hiding, she HAD to go back and help her friends.
4. Remus Lupin
Lupin was by far the best and most competent Defense Against the Dark Arts professor that Hogwarts had while Harry was there, but he's so much more than that. He was willing to do so much to help and protect Harry and he was there for him after Sirius died. Even though Harry pretty much always ignored it, his advice was helpful and his lessons were what allowed Harry to emerge victorious over Voldemort.
5. Colin Creevey
Colin went through a lot in just his first year when he got paralyzed by the basilisk. Even after that he and his brother were willing to join Dumbledore's Army at the drop of a hat. He fought valiantly during the Battle of Hogwarts and deserves to be appreciated and remembered.
6. Mrs. Figg
Arabella Figg is oft forgotten when amazing Harry Potter characters are being discussed, but that doesn't make her any less important. Even though Harry didn't know it, she was always keeping an eye on him for Dumbledore and making sure he was sare. Plus, without Mrs. Figg as a witness during his trial, Harry might've been expelled from Hogwarts and sent to Azkaban.
7. Firenze
Firenze saved Harry's life during his very first year and remained helpful throughout his time at Hogwarts. In Harry's fifth year, he became the Divination professor at Dumbledore's request, despite the fact that this alienated him from his herd.
8. Aberforth Dumbledore
Dumbledore never mentioned his family to Harry, but they're still pretty rad. After Sirius died, Aberforth kept an eye on Harry through the mirror that he gave him. Aberforth also helped out the students still at Hogwarts while Harry, Ron, and Hermione collected Horcruxes. He was helpful when they came to him and fought with them during the Battle of Hogwarts.
9. Narcissa Malfoy
Even though her sister, husband, and son all became Death Eaters, she did not. She wasn't the greatest. She did have pure-blood ideologies, but given the family she grew up with and her agreeable personality, it's understandable (though it's no excuse). She was brave and defiant when it mattered, though. She slighted Voldemort twice to save protect Harry (and Draco), and that made all the difference for Harry and the Wizarding War in the end.
10. Rubeus Hagrid
Hagrid was Harry's first friend at Hogwarts and he was the one that really introduced Harry to the wizarding world. He was always there if they needed help or just wanted a cup of tea. He brought Harry to Dumbledore when his parents were killed and was willing to die for him in Deathly Hallows.