Beacon was a purple bird shaped robot that could fly at supersonic speeds. It was built with a powerful alloy and could destroy stuff simply by ramming into it.

Beacon first appeared in episode 4 "Chaos Emerald Chaos", where it goes with Eggman to get the green Chaos Emerald. It gives Sonic a hard time before the latter beats it with a Power Ring. A second Beacon appears in episode 12 "Beating Eggman, Part 1", where it protects Eggman's base from GUN.

E-11 Beacon - Sonic X/Sega