Yes, the monk St. Cyril and the bishop St. Methodius, blood brothers who together were apostles to the Slavic peoples in the 800's and helped convert all that part of Europe (Germany and Austria and Czechoslovakia, I think, or thereabouts). They invented the Cyrillic alphabet in order to write the Bible in the Slavs' own language. They're much honored in Eastern Europe, Russia and so on--
Wait a second.
Cyril and Methodius are great, but didn't February 14 used to belong to someone else...?
Dang novus ordo calendar. ;) To the 1962 Missal, quick!
Now that's more like it.
Update: I just had to draw attention to the excellent link posted by Gary Keith Chesterton in the comments. :)