Dumbledore's Army

Dumbledore's Army (also known as the D.A.) was a group of students. It was formed by Harry Potter, Ron Weasley and Hermione Granger when Dolores Umbridge refused to teach the students defense against the Dark Arts. The script was also meant to oppose the ministry of magic. During the second Wizard War, the team was reestablished during the Battle of Astronomy Tower and  led by Neville Longbottom, Ginny Weasley, and Luna Lovegood when Lord Voldemort's take over the magic world came to be.

Former leaders

 * Harry Potter (co-founder, co-leader and teacher in Defense against the Dark Arts)
 * Hermione Granger (co-founder and member; jinxed the parchment to those who cheated the group)
 * Ron Weasley (co-founder and member; third in command)
 * Neville Longbottom (acting co-leader; reestablished team during Voldemort's rise to power; formerly)
 * Luna Lovegood (acting leader and member; re-established team during Voldemort's rise to power)
 * Ginny Weasley (acting leader, member and re-established team during Voldemort's rise to power)

Former Members

 * Angelina Johnson (member and student; graduated from Hogwarts, rejoined team during the Battle of Hogwarts)
 * Alice Tolipan
 * Alicia Spinnet
 * Anthony Goldstein
 * Cho Chang
 * Colin Creevey (deceased)
 * Cormac McLaggen
 * Dean Thomas
 * Dennis Creevey
 * Ernie Macmillan
 * Fred Weasley (member and student; returned to Hogwarts to fight in the battle; deceased)
 * George Weasley
 * Hannah Abbott
 * Justin Finch-Fletchley
 * Katie Bell
 * Lavender Brown (deceased)
 * Leanne
 * Lee Jordan
 * Luca Caruso
 * Maisy Reynolds
 * Marietta Edgecombe (member, only joined because Cho forced her to; betrayed the team to Umbridge to protect her mother's job)
 * Michael Corner
 * Neville Longbottom
 * Nigel Wolpert
 * Padma Patil
 * Parvati Patil
 * Romilda Vane
 * Seamus Finnigan
 * Susan Bones
 * Terry Boot
 * Zacharias Smith (abandoned the battle of Hogwarts)
 * Several unnamed students from Gryffindor, Hufflepuff, and Ravenclaw

Allies

 * Albus Dumbledore
 * Weasley family
 * Arthur Weasley
 * Molly Weasley
 * Percy Weasley
 * Bill Weasley
 * Fleur Delacour
 * Oliver Wood (returned to Hogwarts to fight in the Battle of Hogwarts against Voldemort and his Death Eaters)
 * Hogwarts staff and students
 * Minerva McGonagall
 * Horace Slughorn
 * Filius Flitwick
 * Sybill Trelawney
 * Rubeus Hagrid
 * Pomona Sprout
 * Hogsmeade residents
 * Aberforth Dumbledore
 * Order of the Phoenix
 * Sirius Black (deceased)
 * Nymphadora Tonks (deceased)
 * Remus Lupin (deceased)
 * Kingsley Shacklebolt
 * Various other wizards and witches
 * Bewitched suits of armour and statues (100+)
 * House-elves (100+)
 * Kreacher
 * Grawp
 * Centaurs (50+)
 * Peeves
 * Buckbeak
 * Thestrals
 * Several ghosts
 * Nearly Headless Nick
 * Helena Ravenclaw
 * Portraits of Hogwarts
 * Acromantulas (100+)

Former Enemies

 * Dolores Umbridge
 * Inquisitorial Squad (disbanded)
 * Draco Malfoy (defected the Death Eaters, abandoned during the Battle of Hogwarts)
 * Vincent Crabbe
 * Gregory Goyle
 * Pansy Parkinson
 * Ministry of Magic (under Voldemort's control
 * Tom Riddle/Lord Voldemort
 * Death Eaters
 * Bellatrix Lestrange (Second-in-command; killed by Molly Weasley in defense of her daughter Ginny)
 * Lucius Malfoy (formerly; defected the Death Eaters, abandoned during the Battle of Hogwarts)
 * Narcissa Malfoy (formerly; defected the Death Eaters, abandoned during the Battle of Hogwarts)
 * Zacharias Smith (defected and cled during the Battle of Hogwarts)