There are the Slavs, Nordics and Celtics. Are there any other ethnic groups about as broad in Europe?

No

Explanation:

The three major ethnic groups of Europe are the Slavic people, Germanic (Nordic) people, and Celtic people. The Slavic people dominate the central and eastern part of the continent, as well as the Balkans. The Germanic people dominate Scandinavia, and parts of Central and Western Europe, while the Celtic people dominate Western Europe and the Iberian peninsula. there are other ethnic groups in Europe, but they are much smaller. Some of them are the Finno-Ugric people, Greek people, Italic people etc.