The main aim of this research is to present Celtic languages on the British Isles and their connection to contemporary English. It is evident that the English language has gone through different changes over the time. It has been shaped by many new words, brought with new inhabitants from different areas. The changes enriched the English language. The enrichment of the English language influenced its huge expansion, making it the second most frequently spoken language in the world, with Mandarin in the first place. The English language could not be created by itself, in isolation. It was influenced by other languages in order to expand its existence. The Celtic influence on the English language can be seen mostly in place names when it comes to vocabulary and in various grammatical features. The Celtic languages of the British Isles are divided in two main groups: Goidelic and Brittonic (Brythonic) and their geographical position and influence of their linguistic features on the Present Day English is observed.