Hero of the Horde: Grievous

This title will be awarded to the top 0.5 players for each Battlegroup. - At end of season 14.
Only people in RBG will be able to obtain this title.
In order to get the title you will require 50 games played in the current season (Season 14)
Usually it takes 2600Rating+ to obtain this titles, but i varies from each Battlegroup.

Here is the link to check both EU and US Battlegroups:
http://www.wowwiki.com/Battlegroup

Other titles for RBG:
Scout: 1100 Rating in the RBG Bracket.
Grunt: 1200 Rating in the RBG Bracket.
Sergeant: 1300 Rating in the RBG Bracket.
Senior Sergeant: 1400 Rating in the RBG Bracket.
First Sergeant: 1500 Rating in the RBG Bracket.
Stone Guard: 1600 Rating in the RBG Bracket.
Blood Guard: 1700 Rating in the RBG Bracket.
Legionnaire: 1800 Rating in the RBG Bracket.
Centurion: 1900 Rating in the RBG Bracket.
Champion: 2000 Rating in the RBG Bracket.
Lietenant General: 2100 Rating in the RBG Bracket.
General: 2200 Rating in the RBG Bracket.
Warlord: 2300 Rating in the RBG Bracket.
High Warlord: 2400 Rating in the RBG Bracket.
In Service of the Horde: Win 1/25/75/150/300 Rated Battlegrounds.

Titles mentioned above is Horde side Only.