The Dramiel is the fastest Frigate in EVE.
The Claw is the fastest of the Interceptor group, but a Dramiel running an MWD is faster because of its lower mass, since MWD speed boost is affected by ship mass.
Things that affect speed are
Here's a table with the calculated speeds (base ship speed, max fitted/rigged and MWD, each without skill bonus and finally with all skills at level V3):
Here are the results as CSV. They were calculated from a subset of the CCP database export with this Python script, using the speed formulas from the top speed calculation guide and the Aenigma formula for bonus stacking penalties. Some calculated speeds were cross-checked against Pyfa.
1 The speed bonuses from the Overdrive modules and Rigs are subject to severe stacking penalties, making it fairly useless to cram more than 2-3 of these in your ship in total. However for the purpose of finding the fastest ship it was assumed that all ships had their low slots full of Overdrive modules and their Rig slots full of Auxiliary Thrusters. This is not a sensible build to fly around in though.
2 These bonuses affect the velocity directly and therefore don't matter for a ship comparison. They were not taken into account here.
3 Due to neither implants nor Leadership/Gang bonuses being applied, this is not the fastest these ships can go.