A third-generation Badnik. Tunnelbots are advanced drillers and are capable of boring through the toughest rock. Since they are capable of flight, they can also burrow into raised or airborne structures.
Tunnelbots have appeared in the two-part Sonic story, Robotnik's Revenge. Robotnik deployed several Tunnelbots and other Badniks to demolish Sonic's secret underground base in the Emerald Hill Zone.
A single Tunnelbot also appeared in Carnival Night Conspiracy, as part of the badnik force used by the Marxio Brothers to defend the Carnival Night Zone.
The Tunnelbot appeared in Sonic the Hedgehog 3 as the sub-boss in the Marble Garden Zone.