Wizards, Witches and Beings: O
Oakby,
Idris
(1872 - 1985)
Founder of the S.S.S. (Society for the Support of Squibs).
JKR's Wizard of the month for October 2006 (JKR).
Oblansk (or Obalonsk), Mr. 
The Bulgarian Minister for Magic, who watches the Quidditch World Cup along with Cornelius Fudge in the top box. He understands English, but pretends not to (GF8).
Oddpick, Winkus
Wrote an editorial to the Daily Prophet entitled "Why can't goblins be more like elves?" after the Chipping Clodbury riot (DP).
Odo the Hero
After drinking quite a lot of wine, Hagrid and Horace Slughorn sang a lachrymose song about Odo, a wizard who died young (HBP22). Hagrid and Charlie Weasley sang the song at Bill and Fleur’s wedding as well (DH8).
O'Flaherty
The name Professor Binns uses to refer to Seamus Finnigan; he doesn’t seem to know his students particularly well (CS9).
Ogden
Presumably the creator of Ogden's Old Firewhiskey. We do know that there is at least one wizarding family named Ogden (see below).
Ogden, Bob
A "short, plump man" who worked for the Department of Magical Law Enforcement (HBP10). Ogden wore glasses so thick that they made his eyes look like specks. Dumbledore interviewed Ogden during his search for information about Tom Riddle's family; Ogden had visited the Gaunt house to follow up after Morfin Gaunt attacked Muggle Tom Riddle, and there been attacked himself (HBP10).
Ogden, Tiberius
Wizengamot elder who resigned in protest when Fudge appointed Dolores Umbridge as the first Hogwarts High Inquisitor (OP15); friend of Professor Tofty of the Wizarding Examinations Authority (OP31).
Ogg 
Gamekeeper at Hogwarts during Molly Weasley's era, probably the man who held the job before Hagrid. Molly seemed to be rather fond of him (GF31).
Ogg's name has interesting associations from both the Bible and British folklore. In the bible, Ogg, King of the Bashan, tried to deter the Israelites from conquering the promised land; Ogg has become a name for giant in the Hebrew language. Ogg may also be a reference to the legendary British giants Gog and Magog who guarded the entrance to the royal palace. Their names also have their source in the bible. (--Brewer's Dict. and Lexicon reader Tomer Navot).
Oglethorpe,
Dunbar 
(b. 1968)
Chief of Q.U.A.B.B.L.E., the Quidditch Union for the Administration and Betterment of the British League and its Endeavors (fw).
O'Hare, Darren
Keeper for the Kenmare Kestrels 1947 - 1960; he captained the Irish National Team and invented the Hawkshead Attacking Formation (QA8).
Olaf 
(1100s)
Norwegian cousin of Goodwin Kneen of Yorkshire in the 1100s. Kneen wrote to him describing the 12th Century version of "Kwidditch." (QA3).
Oldridge,
Chauncey 
(1342 - 1379)
Wizard who was the first known victim of Dragon Pox (fw25).
However, Gunhilda Kneen in the 1100s had to sit out a game of Quidditch with a case of Dragon Pox (QA3). Oldridge was Rowling's "Wizard of the Month" for July 2005.
Oliphant,
Gondoline
(1720 - 1799)
A famous troll expert who was clubbed to death in the Cotswolds (fw).
'Gondoline' means small gondola in Italian; it is also the title of
an 1831 poem by Alonzo Lewis "To Gondoline" "Of the soft flowing
stream/
And muse upon its gentle tide/We 'll roam along the flowery side/
In many a pleasant dream...."
'Oliphant' is a Scottish family name, and is M.E. for 'elephant.'
Oliphant was JKR's "Wizard of the Month" for April 2005.
Ollerton,
Barnaby, Bill & Bob 
Brothers who founded the Cleansweep Broom Company in 1926. Theirs was the first racing broom to be racing broom, and it changed the market (QA9).
Ollerton,
Gifford
(1390-1441)
Famous giant slayer; killed the famous giant Hengist of Upper Barnton (fw26).
Ollivander, Mr. Garrick 
(born 25 September)
An old wandmaker – “the best” – who who runs Ollivander's on Diagon
Alley (HBP6). He has eerie, moon-like eyes and makes Harry a bit uncomfortable, as he seems just as fascinated by the power of wands used for evil as those used for good. Ollivander remembers every wand he has ever sold, and greets people by rattling off the specifications of their wands (PS5, DH24).
Ollivander was kidnapped shortly after Voldemort’s return was made public, in summer 1996; Voldemort was in search of information about his and Harry’s wands (HBP6, DH5). He was held captive in Malfoy Manor for a year and a half, tortured, and forced to make wands (DH24). He escaped with the help of Dobby (DH23) and hid at Auntie Muriel’s for the remainder of the war (DH26).
In the films, Ollivander is played by John Hurt (IMdb). Ollivander's first name was revealed on Pottermore, along with the fact that his last name probably means "possessor of an olive wand" (Pm).
Oona
(1100s)
Innkeeper in Yorkshire in the 1100s. She provided the local "Kwidditch" team with the barrels they used for goals and afterwards, gave free mead all night to celebrate the team's victory over Ilkley (QA3).
