Lovok

Colonel Lovok was a member of the Tal Shiar. He worked along side with the Obsidian Order in their plan to destroy the Founders.

At some point Lovok was replaced by a Changeling, unbeknownst to his colleagues and conspirators. His presence in the plot allowed the Dominion to have enough forewarning to evacuate the Founder's homeworld and set a trap for the joint Tal Shiar-Obsidian Order fleet.

The Changeling revealed itself to Odo and Garak when it assisted them in escaping from his warbird during the battle.