Wargs

Wargs were monstrous wolf like beasts in service to the Dark Lord Sauron. They were commonly found in the employ of the armies of Orcs.

Attack upon the archers
Wargs were among the creatures sent by the wizard Saruman against the Rohirrim during the Battle of Helm's Deep. As Saruman's army neared the fortress, the Wargs of Isengard charged at the archers, wounding most of them but managing to kill some.

Trivia

 * In Ralph Bakshi's The Lord of the Rings, Wargs appear only at the Battle of Helm's Deep unlike the novels in which some of the wargs ambush the Fellowship of the Ring on their journey to the mines of Moria.
 * Wargs are not used as mounts by the Orcs during the skirmish and after the attack upon the archers they are not seen again.