Sonic
Sonic's canonical velocity reaches 767 miles per hour, precisely the speed of sound that granted him his name. Official SEGA documentation confirms that with power-ups, he approaches Mach 5, approximately 3,800 miles per hour. Players have witnessed this blue streak circumnavigate loops, outpace missiles, and leave afterimages across Green Hill Zone for over three decades.
His speed is observable, visceral, and fundamentally tied to his identity. Remove Sonic's velocity and you remove his essence entirely.
Time
Time moves at precisely one second per second, a rate so consistent that it has become the baseline against which all speed is measured. Yet this apparent constancy conceals remarkable complexity. Near black holes, time dilates to near-standstill. At the Planck scale, physicists debate whether time exists at all.
More significantly, time's speed is definitionally unmeasurable. One cannot observe time moving faster or slower without reference to time itself, a self-referential impossibility.