Tracy Schwartz, the fiddle player for the New Lost City Ramblers. Although he didn't play accordion with the NLCR, he does play cajun music on the diatonic one row button accordion.

I've noticed a large number of players who don't fit Len's requirements showing up in this thread. People like Myron Florin, Art Van Damme, Peewee King, Garth Hudson, Clifton Chenier, Marc Savoy and Len Wallace for that matter, don't belong here, since they are well known for being accordion players. Len was looking for people who were well known, but NOT as accordion players.