H – Harrium (Harry James Potter)
He – Hermionium (Hermione Jean Granger)
Li – Lilium (Lily Potter; either Harry's mother or daughter)
Be – Bellatrixium (Bellatrix Lestrange)
B – Burbagium (Charity Burbage's last name; Deathly Hallows character; Muggle Studies professor at Hogwarts)
C – Changium (Cho Chang's)
N – Nottium (The Death Eater or his son, Theodore Nott, who's in Slytherin)
O – Ollivandium (The wand-maker, Ollivander)
F – Fredium (Fred Weasley)
Ne – Nevillium (Neville Longbottom)
Na – Narcissium (Narcissa Malfoy; Draco's mother)
Mg – McGonagallium (Minerva McGonagall)
Al – Albusium (Albus Percival Wulfric Brian Dumbledore… I think I got that right; I'm going from memory)
Si – Sinistrium (Aurora Sinistra; Astronomy professor at Hogwarts)
P – Peevesium (Peeves the Poltergeist)
S – Seamusium (Seamus Finnegan)
Cl – Claggium (Elfrida Clagg; Chieftainess of Warlock's Council; also on a "Famous Witches and Wizards Card")
Ar – Arabellium (Arabella Figg; Squib who lives near the Dursleys)
K – Karkaroffium (Igor Karkaroff; Headmaster of Durmstrang)
Ca – Crabbium (Vincent Crabbe)
Sc – Scorpiusium (Scorpius Malfoy; Draco's son)
Ti – Pettigrewium (Peter "Wormtail" Pettigrew)
V – Voldemortium (Lord Voldemort; this one was a no-brainer)
Cr – Carrowium (Amycuz and Alecto Carrow; brother and sister; Death Eaters)
Mn – Minervium (Minerva McGonagall)
Fe – Fleurium (Fleur Delacour)
Co – Colinium (Colin Creevey)
Ni – Nickium (Nearly Headless Nick or Sir Nicholas De Mimsy Porpington; House Ghost for Gryffindor)
Cu – Crouchium (Barty Crouch Sr./Jr.)
Zn – Zabinium (Blaise Zabini; Slytherin)
Ga – Grawpium (Grawp; Hagrid's half-brother)
Ge – Georgium (George Weasley)
As – Alastorium (Alastor "Mad-Eye" Moody)
Se – Severusium (Severus Snape)
Br – Broomstickium (Filler for lack of a name… lol Broomstick)
Kr – Krumium (Viktor Krum)
Rb – Rabastanium (Rabastan Lestrange; Bellatrix's brother-in-law)
Sr – Siriusium (Sirius "Padfoot" Black; Harry's godfather, duh!)
Y – Yaxlium (Yaxley – what's his first name? – Death Eater)
Zr – Zacharium (Zacharias Smith)
Nb – Dunbarium (Dunbar Oglethorpe; Q.U.A.B.B.L.E. Chief)
Mo – Mollium (Molly Weasley)
Tc – Twycrossium (Wilkie Twycross; Apparition Instructor)
Ru – Rubeusium (Rubeus Hagrid)
Rh – Randolphium (Randolph Keitch; Pro Quidditch player for the Falmouth Falcons)
Pd – Padmium (Padma Patil)
Ag – Agrippium (Cornelius Agrippa; Author who was imprisoned by Muggles)
Cd – Cedricium (Cedric Diggory)
In – Ignotusium (Ignotus Peverell; Deathly Hallows character)
Sn – Snapeium (Severus Snape)
Sb – Blaisium (Blaise Zabini; Slytherin)
Te – Teddium (Teddy Lupin; Remus Lupin's son, Harry's godson; Deathly Hallows character)
I – Igorium (Igor Karkaroff; Headmaster of Durmstrang)
Xe – Xenophilium (Xenophilius Lovegood; Luna's father)
Cs – Amycusium (Amycus Carrow; Death Eater)
Ba – Bagshotium (Bathilda Bagshot; Author of AHistoryofMagic)
Lu – Luciusium (Lucius Malfoy; Draco's father)
Hf – Hufflepuffium (Hogwarts co-founder, Helga Hufflepuff)
Ta – Tobiasium (Tobias Snape; Severus's father)
W – Weaslium (Weasley)
Re – Remusium (Remus Lupin)
Os – Olympium (Olympe Maxime; Headmistress of Beauxbatons Academy)
Ir – Irmium (Irma Pince; Hogwarts librarian)
Pt – Phoenixium (For lack of a name; the magical creature, Phoenix)
Au – Argusium (Argus Filch)
Hg – Hugoium (Hugo Weasley; Ron's son)
Tl – Trelawnium (Sibyll Trelawney; Divination professor at Hogwarts)
Pb – Pure-bloodium (For lack of a name; pure-blood)
Bi – Biliusium (Bilius Weasley; I think he was Ron's uncle or something; if not, Ron's middle name)
Po – Potterium (Potter)
At – Aberforthium (Aberforth Dumbledore; Albus's brother)
Rn – Ronaldium (Ronald Bilius Weasley)
Fr – Frankium (Frank Longbottom; Neville's father)
Ra – Draconium (Draco Malfoy; I think his longer Latin name is Draconis… Oh, well… lol)
Lr – Lockhartium (Gilderoy Lockhart; dumbass DADA professor in Harry's second year)
Rf – Rufusium (Rufus Scrimgeour; Minister of Magic after Fudge and before Thicknesse)
Db – Baddockium (Malcolm Baddock; Slytherin)
Sg – Greengrassium (Daphne Greengrass; Slytherin)
Bh – Bulstrodium (Millicent Bulstrode; Slytherin)
Hs – Higgsium (Terrence Higgs; Slytherin; was seeker on the Quidditch team in Harry's first year)
Mt – Mariettium (Marietta Edgecombe; Ravenclaw; Cho Chang's friend)