Forgot about this one yesterday. In the Lutheran Service Book commemorations on the church year calendar, C.F.W. Walther is remembered on May 7, the day he died and became a member of that "great cloud of witnesses" of which the author of Hebrews wrote (Heb. 12:1).
To read more about Walther, click here to go to his page on the Concordia Historical Institute's website (although note that they give the day of his death as May 17, not May 7).
Check out this page also at Wikipedia.