Tyler Lanier Walker (born May 15, 1976 in San Francisco, California) is a Major League Baseball relief pitcher who is currently playing for the Washington Nationals. He is an alumnus of San Francisco University High School and University of California, Berkeley. Walker has pitched for the New York Mets (mlby2002), San Francisco Giants (mlby2004-mlby2006, mlby2007-mlby2008), Tampa Bay Devil Rays (Tampa Bay Rays) (2006), and Philadelphia Phillies (2009).