Dead
Aberforth Dumbledore
Arabella Figg
Colin Creevey
Dedalus Diggle
Elphias Doge
Hestia Jones
Most of the Teachers who taught, during Harry's time at school.
Oliver Wood and His whole Family.
Rubeus Hagrid

Offlimits
Audrey Weasley (Percy's Wife)
Angelina (Johnson) Weasley
Arthur and Molly Weasley
Bill, Charlie, Percy and George Weasley
Cho Chang
Fleur (Delacour) Weasley
Fred Weasley (Son of George & Angelina)
Harry Potter
Hannah (Abbott) Longbottom
James Potter (Son of Harry & Ginny)
Katie Bell
Kingsley Shacklebolt
Lavender Brown
Lee Jordan
Luna (Lovegood) Scamander
Molly Weasley (Daughter of Percy & Audrey)
Mundungus Fletcher
Neville Longbottom
Rolf Scamander
Seamus Finnigan
Susan Bones
Sturgis Podmore
Teddy Lupin
Victoire (Weasley) Lupin (Daughter of Bill & Fleur)
Many More

Playable
Albus Potter (Son of Harry & Ginny)
Anthony Goldstein
Any Slytherin in, above or below Draco's time at school.
Dean Thomas
Dennis Creevey
Dominique Weasley (Daughter of Bill & Fleur)
Draco Malfoy
Ernie Macmillan
Hugo Weasley (Son of Ron and Hermione)
Justin Finch-Fletchley
Lily Potter (Daughter of Harry & Ginny)
Louis Weasley (Son of Bill & Fleur)
Lucius & Narcissa (Black) Malfoy
Lucy Weasley (Daughter of Percy & Audrey)
Michael Corner
Padma Patil
Parvati Patil
Rose Weasley (Daughter of Ron and Hermione)
Roxanne Weasley (Daughter of George & Angelina)
Terry Boot
Zacharias Smith
Many More

Reserved
Hermione (Granger) Weasley

Already Played By Someone
Ron Weasley
Ginny (Weasley) Potter
Scorpious Malfoy (son of Draco Malfoy)