Here is a list of the Canon Character available for adoption. They go in alphabetical order by last name. Now, although the list is here if you want one you must fill out an application to have one. This list is to merely keep track and so I do not have to go through the struggle of denying people.
A
Hanna Abbott
B
Katie Bell
Sirius Black
Amelia Susan Bones
Susan Bones
Terry Boot
Lavender Brown
C
Cho Chang
Penelope Clearwater
Michael Corner
Crabbe Sr.
Vincent Crabbe
Colin Creevey
Dennis Creevey
Bartemius "Barty" Crouch Sr.
Bartemius "Barty" Crouch Jr.
D
Fleur Delacour
Gabrielle Delacour
Amos Diggory
Cedric Diggory
Antonin Dolohov
Albus Dumbledore
Vernon Dursley
Petunia Dursley
Dudley Dursley
E
Marietta Edgecombe
F
Argus Filch
Justin Finch-Fletchley
Seamus Finnigan
Mundugnus Fletcher
Fillius Flitwick
Cornelius Fudge
G
Anthony Goldstein
Goyle Sr.
Gregory Goyle
Hermione Granger
Fenrir Greyback
H
Rubeus Hagrid
Rolanda Hooch
Mafalda Hopkin
J
Angelina Johnson
Lee Jordan
K
Igor Karkaroff
Viktor Krum
L
Bellatrix Lestrange
Gilderoy Lockhart
Neville Longbottom
Luna Lovegood
Xenophilius Lovegood
Remus Lupin
M
Ernie Macmillan
Walden Macnair
Draco Malfoy
Lucius Malfoy
Narcissa Malfoy
Olympe Maxime
Minerva McGonnagall
Cormac McLaggen
Alastor "Mad-Eye" Moody
P
Pansy Parkinson
Padma Patil
Parvati Patil
Peter Pettigrew
Ima Pince
Poppy Pomfrey
Harry Potter
R
Tom Marvolo Riddle
Augustus Rookwood
Evan Rosier
Madam Rosmerta
S
Kingsley Shacklebolt
Stan Shunpike
Rita Skeeter
Horace Slughorn
Severus Snape
Alicia Spinnet
T
Dean Thomas
Nymphadora Tonks
Sybill Patricia Trelawney
W
Arthur Weasely
William Arthur "Bill" Weasley
Charlie Weasley
Fred Weasley
George Weasley
Ginny Weasley
Molly Weasley
Percy Weasley
Ron Weasley
Oliver Wood
If there are jumps in letters, it is not because I forgot them, it is because I deliberately skipped over them. There were no characters in the books with those last names that held a lot of significance to the stories. Now, bear in mind that there are also some Death Eaters scattered in there, so if you pick a canon that you do not know google him before you claim him.