[Galaico]

The Celtic influence in Spain, as in most Western Europe, was basically cultural and linguistical. There never was anykind of mass migration from Central to Western Europe.

As for the Germanic influence, it is estimated that 150,000 to 300,000 Germanics (Visigoths and Suebi) settled in Spain after the fall of the Roman Empire. Taking into account that the population of Spain at the time was of about 6,000,000 we could talk about an influence of 2-5%. Not much really.