One of the most influential (to those in the know) contemporary harmonica players ever was William Clarke. Now, guys like the Walters and the Sonny Boys (and others) came before him and really laid the foundation for Clarke to build upon, but William Clarke took what they created (a unique roll within the Blues for my favorite instrument) and built upon it in a new way that connected the Blues and Jazz through the voice of the harmonica.
He learned his craft from George "Harmonica" Smith but ultimately developed a very personal style. His mastery of the harmonica was unique; his note selection and phrasing were so creative and individual, his tone and style all his own.
If you're interested in Blues Harmonica and haven't heard of William Clarke, you can learn a little more about him...