If you don't know the name then buy yourself any compilation album of recordings Howlin' Wolf made for Chess Records in the 1950s and '60s. That's him on lead guitar. Put simply it's some of the best electric blues guitar playing of all time. He also worked with Muddy Waters, but it's the Wolf's recordings that have won him a place in history - and rightly so. They are fabulous.
In latter years he's been a regular contributor to the Crossroads Guitar Festivals organised by Eric Clapton, who has made no secret of his fervant admiration of Sumlin's playing. (Here is a great clip from last year's festival - note E.C. singing along!) And the fact that Mick Jagger and Keith Richards paid for his funeral speaks volumes for his influence on them and therefore subsequent generations of musicians.
I met him once. I never tire of retelling the story, as is evidenced by the fact that I told it here as early as October 2006, just after I started blogging. You can read it here if you like - I hope my writing has improved since then... but the profound nature of his comments have never left me, and in times of self doubt (of which there are many) they come back to me along with his enthusiasm for music and the kindness and encouragement that he showed to me, a total stranger among the many that someone like him must have met. My brief encounter with him showed him to be a absolute gentleman, and I've not heard or read anything anywhere that contradicts that.
His importance in the story of the electric guitar cannot and must not be underestimated.