Isn't Sherlock an English name? And isn't Sherlock's greatest enemy's name Professor Ó Muircheartaigh, Anglicized as Professor Moriarty?
Yes; Sherlock is from an Anglo-Saxon word that either means fair hair or short hair.
Moriarty is one of the Anglicizations of “Ó Muircheartaigh”; the other most common forms are Murtagh/Murtaugh, Murdock/Murdoch, and even McMurtry and McCurdy (from the “Mac Mhuircheartaigh” variant).