Pen

Pen as seen in Sonic Advance

'Pen is a robotic penguin enemy found in Sonic Advances Ice Mountain Zone. They walk back and forth, and when approached, they make a stop and launch snow balls at the player. Just jump over the snowball and hit the badnik, and you'll be fine.

A newer model of Pen reappears in Sonic Advance 2's Ice Paradise Zone and behaves similarly to Sonic 3's Penguinator badnik in the sense that rather than launching a projectile it will instead charge at the player. Unlike Penguinator however, this version of Pen does not stand up at any point.