Mark Ratkiller [Krysoboi]
Mark's nickname is an ironic translation of L muricidus, "mousekiller," which was a Roman slur against cowardly soldiers.
Some editions introduce Mark as the "commander of a special century." Bulgakov's notes show that some extraordinary (i. e. outside the regular military structure) centuriae fulfilled police functions.
Mark's boots in Chapter 2 are an anachronism that might remind the reader of the Civil War in Russia instead of First Century Judea.