Walker is an enemy Badnik encountered in Panic Puppet Zone, the seventh level of Sonic 3D: Flickies' Island.
A spider-like Badnik that strolls back in a straight line, firing projectiles from any of its quad cannons. Attack with a Spin Dash or jump to smash it. Unlike the Badniks in the first six levels on Flickies' Island, the Panic Puppet Badniks do not contain Flickies as Dr. Eggman didn't have enough time to put the Flickies into them; the birds can be found in miniature glass pods, still awaiting to be placed into a Badnik.
The name of this Badnik is conjectural, as no official name has been given to it. The name comes from the level editor in a development build of Sonic 3D that is included as a bonus feature in Sonic 3D: Director's Cut. Jon Burton has confirmed that the name was used in the original game.