Achievements

On a Metric Ton of Missions
Draenor Garrison
#9140
On a Mission
Draenor Garrison
#9133
On A Roll
Battle
#6618
On Brand
The War Within
#40523
On Metzen!
Winter Veil
#273
On the Blade's Edge
Outland
#1193
On the Blade's Edge (char specific hidden copy)
Outland
#39941
On the Offensive
Shadowlands
#15035
On The Rocks
Lich King Dungeon
#1919
On the Shadow's Trail
Draenor
#9528
On the Shadow's Trail
Draenor
#9529
On Wings of Nether
The Burning Crusade
#898
Once Bitten, Twice Shy (10 player)
Lich King Raid
#4539
Once Bitten, Twice Shy (25 player)
Lich King Raid
#4618
One Does Not Simply Walk Into Harandar
Midnight
#41804
One Hump or Two?
Mounts
#4888
One Light in the Darkness
Lich King Raid
#12387
One Light in the Darkness (10 player)
Raids
#3158
One Light in the Darkness (25 player)
Raids
#3163
One Man's Trash...
Pandaria
#7283
One Many Army
Pandaria
#7317
One Night in Karazhan
Legion Dungeon
#11430
One of Everything, Please
Dragon Isles
#16621
One of Us! One of Us!
Draenor
#9434
One Rank Higher
War Within Raid
#41119
One Step at a Time
Pandaria
#7324
One Steppe Forward, Two Steppes Back
Pandaria
#6539
One Steppe Forward, Two Steppes Back (char specific hidden copy)
Pandaria
#39999
One That Didn't Get Away
Fishing
#878
One Two Three You Don't Know About Me
Battle for Gilneas
#5249
One Warband Mentor: Midnight
Characters
#42328
One Warband Mentor: The War Within
Characters
#19470
One-Up
Pandaria Raid
#8077
One, Two, Ral'kala's Coming for You
Prey
#63453
Only the Penitent...
Cataclysm Raid
#5799
Onyx Panther
Mounts
#3896
Onyxia kills (Onyxia's Lair)
Classic
#1098
Onyxia's Lair (10 player)
Lich King Raid
#4396
Onyxia's Lair (25 player)
Lich King Raid
#4397
Onyxia's Lair (Level 60)
Raids
#684
Oondasta
Remix: Mists of Pandaria
#20020
Oondasta Guild Run
Pandaria Raid
#8138
Oondasta kills
Mists of Pandaria
#8147
Opening of the Dark Portal
The Burning Crusade
#655
Operation Counterattack
Ashran
#9217
Operation Counterattack
Ashran
#9408
Operation: Floodgate
War Within Dungeon
#41339
Operation: Gnomeregan
Events
#4786
Operation: Mechagon Guild Run
Battle Dungeon
#13893
Operation: Shieldwall
Pandaria
#8205