Alan

Also Portuguese: https://www.behindthename.com/name/alan/top/brazil

Also Spanish:

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https://es.m.wiktionary.org/wiki/Alan
https://www.ine.es/widgets/nombApell/index.shtml?L=1

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Also Polish:

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https://pl.m.wikipedia.org/wiki/Alan
https://pl.m.wiktionary.org/wiki/Alan
https://www.behindthename.com/name/alan/top/poland

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Also Czech:

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https://cs.m.wikipedia.org/wiki/Alan
https://en.m.wiktionary.org/wiki/Alan#Czech
https://www.behindthename.com/name/alan/top/czech

Also used in Czechia and Slovakia.

Also Niçard: http://www.sourgentin.org/cours-de-nissart/les-prenoms/
http://www.academiaoccitana.eu/oc/15/239/Los-lexics-especializats/Los-prenoms-occitans
You'll find bearers on social media.

Also Gascon, Provençal and Languedocian: https://ieo-oc.org/spip.php?page=article&id_article=290 --- Source: Institut d'Estudis Occitans

Allegedly also used in Galician: https://gl.wikipedia.org/wiki/Lista_de_nomes_masculinos_en_galego#N
http://www.ige.eu/igebdt/esq.jsp?idioma=gl&ruta=onomast/nomes.jsp

Also used in Slovak: https://sk.wikipedia.org/wiki/Alan_(prv%C3%A9_meno)

Also used in Czech: https://cs.wikipedia.org/wiki/Alan --- including stats

Alan and Alen (a far more common variant) are also common in Croatia.

Also a boys name in Slovenia.

A mistake in the website name's explaination: Alan is Scottish, English, Breton (with a different pronunciation).