If you visit Baseball-Reference.com and look at a list of players who have played for both the Red Sox and Washington Nationals, Bill Lee is listed despite never donning a Nationals uniform. The reason for this, of course, is due to the fact that the Montreal Expos relocated to Washington D.C. after the 2004 season.
So, technically, Bill Lee is one of just six players to play only for both the Red Sox and Expos/Nats. Bill "Spaceman" Lee is, to the best of my knowledge, the only recipient of continued support via graffiti on the wall of the Green Monster.
When Bill Lee was traded to the Montreal Expos for a proverbial bag of balls named Stan Papi, someone responded by spray painting "Who The Hell Is Stan Papi?" on the back of the Green Monster. The Fenway grounds crew cleaned up the graffiti, but the sentence reappeared often during Bill Lee's career until he retired.
Despite technically playing for only the Red Sox and Expos, Bill Lee has pitched for more than a half dozen semi-pro and celebrity teams since his retirement. In 2010, Lee pitched for the Brockton Rox and picked up the win at the age of 63.
There is no player on the Red Sox or Nationals today that comes close to being the character that is Bill "Spaceman" Lee, but perhaps one of the Red Sox relief pitchers will mix things up and bust out an Eephus pitch!