Okay. Here we go, focus. Speed. I am speed.
~ Lightning McQueen
Up, Over and Gone!
~ Sonic the Hedgehog

These are the heroes that can run at speeds unobtainable by normal humans and often have an array of special adaptations and skills as a result: the source of their speed can vary (such as the Speed Force in DC or less defined "sciences" and "magic") but all are linked by the simple fact they are the fastest heroes around.

Good examples of speedsters are: Dash Parr, GoGo Tomago, Goku, Lightning McQueen, Mario, Quicksilver, Sonic the Hedgehog, The Flash and XLR8.