The Egg Walker is a quadrupedal machine operated by Doctor Robotnik from his new Citadel. It is based upon the final boss of Tails' story in Sonic Adventure, though in Sonic the Comic Online, it is depicted with a red colour scheme, and is lacking the weak points on its feet as seen in the game. It is equipped with a powerful laser, but can do a good deal of damage just by stomping around.
Robotnik unleashed the Egg Walker upon a Fabian Vane concert in the Casino Night Zone, where he panicked the crowds and caused some destruction, though his main target was Fabian himself. Having learned his lesson from previous encounters with Fabian and his singing during the war, he disabled the mech's audio receptors. However, Amy Rose was able to put a stop to the attack by firing a USB drive loaded with mp3s Fabian had recorded earlier into one of the sockets below the machine's screen. With Robotnik hindered by Fabian's terrible music playing directly into his brain, the robot was quickly disabled.
- Part of the Egg Walker had previously been seen in Robotnik's "Viper-Walker". This was a combination of the Egg Walker and the Egg Viper also seen in Sonic Adventure. Differences from this model include the addition of a long tail and large arms with claws.