Tamer is a title awarded when you complete the Pet Battle meta-achievement Taming Azeroth, earned by defeating every Pet tamer NPC to be found in Kalimdor, the Eastern Kingdoms, Outland, Northrend and Pandaria.
The title appears before your character's name:
Taming Azeroth, earned by defeating every Pet tamer NPC to be found in Kalimdor, the Eastern Kingdoms, Outland, Northrend and Pandaria.
Patch 5.0.4 (2012-08-28): Added. 
