Whole new class? Probably a Pet class since that's the only truly unique niche I don't see filled.
Class: Pathfinder, Tames and uses the beasts of Thedas to augment their offensive and defensive capabilities. Using expendable animal servants, the Pathfinder excels in tasks such as scouting and drawing enemies into ambushes. Synergizes well with an Artificer to create deadly low man ambushes. The Pathfinder can tame most non magical animals and use them against the enemies in an area. Though slower than a typical warrior or rogue class when it comes to damage, no class is more adept at buying time or probing dangerous areas than the Pathfinder.
Specializations:
Kennel Master. The special Training of the Ferelden Kennel Masters allows the Pathfinder to call upon the legendary Mabari War Hounds in battle. Functionally a Familiar, the Mabari may not be the most potent natural predator in the engagement, but fierce loyalty and a powerful bite make for a strong ally, especially in areas that are lacking any more traditional animals the Pathfinder can exploit.
Wyvern Rider. In certain parts of Thedas, there are those with the exceptional ability to tame and ride the Wyverns of the sweeping deserts, whilst cursory training wouldn't allow the Pathfinder to mount these ferocious beasts and ride into battle, this specialization does expand the Pathfinder's taming ability to include some of the lesser reptilian monsters, including Wyverns and Drakes. The rebellious and strong-willed nature of these creatures means their loyalty is a waning affair, but for a brief moment the Pathfinder can beseech some of the most dreaded monsters of Thedas for aid.
Ranger. Training that focuses more exclusively on the combat prowess of the Pathfinder himself, extensive knowledge of the natural world grants the Pathfinder greater offensive capabilities against most creatures, excluding undead and magical beasts or constructs. Especially deadly with the Axe, the abilities of the Ranger begin to rival that of warriors, add in the Pathfinder's original repertoire and there is no better fighter to have at your back in the wilds of Thedas.