BlenRig
BlenRig is possibly the oldest Auto-Rigger for Blender. It was used in some of the earlier official Blender Open Movies, such as “Caminandes” and “Agent 327”.
Unlike other similar addons which emphasize speed and ease of use, BlenRig’s focuses on delivering an extremely feature-rich film quality character rig.
The addon attempts to do as much of the rigging and weighting work as possible. The full rigging process includes automatic setup of advanced deformers such as Mesh Deform and Lattices.
This extensive functionality requires a somewhat lengthy setup. To aid with that, the newest version of the addon has an Interactive Rigging Assistant Guide built right into the Blender interface.