One of the novels' characters — Rubeus Hagrid — «is known for his thick West country accent» (a quotation from Wikipedia).
In Ukrainian translations of the books (also in Ukrainian dubbing of «HP & the Order of Phoenix» movie) Hagrid speaks some sort of Western Ukrainian dialect, most akin to Hutsul; however, dialectal substrate in his speech is not overwhelming, and he can easily be understood by an average reader.
I wonder how this was rendered in other translated versions. AFAIK, for instance, in Russian version, Hagrid speaks just standard Russian with no peculiarities.