Rogue

Rogues are one of the promoted versions of the Thief (the other being Assassin). They are found in Fire Emblem: The Sacred Stones and Fire Emblem: Radiant Dawn.

Combat
Rogues are much like Assassins when they are first upgraded to this form. For example, they both use the same weapons and have nearly the same stats. Rogues have a smaller constitution than Assassins, less HP, but higher skill.

Rogues, like the other versions of the Thief class exceed in their high Speed and Skill. Although they usually have somewhat mediocre Defense and Resistance they often dodge enough enemy attacks to make up for that. Rouges are are not usually used as exclusive combat units because they usually have realitively low Stength Caps, despite their impressive Strength growths, and also their lower defensive stats come into play.

Assassins usually preform better as strictly combat units because of their better status Caps and growths for combat realated skills.

Abilities
Also, Rogues have different skills. In Fire Emblem: The Sacred Stones, Rogues are the only units that can open Doors and Treasure Chests without the use of a Lockpick item (which Thieves and Assassins use) or a Key. This ability was later eliminated though as in the later games all Thieves and promoted Thieves could open doors and chests without the use of any items.

Promotions
Being the promoted version of the Thief, the Rogue can not be promoted any further. The exception for this is in Fire Emblem: Radiant Dawn. In Radiant Dawn both Sothe and Heather (who are Rouges) can be promoted to the Whisper class, the 3rd Tier class of a Theif (and the promotion of a Rouge).

Characters of this Class
In Fire Emblem: The Sacred Stones, there is a pre-promoted rogue by the name of Rennac and you may choose to promote the thief Colm to this class as well. Although most choose to promote Colm to the Assassin class.

In Fire Emblem: Radiant Dawn, there is a rogue by the name of Heather. Closer to the beginning of the game,the player receives the rogue Sothe. (who in Fire Emblem: Path Of Radiance was an un-promotable Thief)

In Fire Emblem:Thracia 776 there is a rogue by the name of Pahn.