Did Martin Luther write his own Bible? Did Martin Luther compose his own Bible?  I have seen claims to this effect.  By this I believe the claimants meant a Bible that differed from recognized, standard forms, rather than translation into German.
In 1516 the Catholic priest Desiderius Erasmus obtained the Codex Basilensis from the Basel University Library in Basel, Switzerland.  This Codex contained seven manuscripts of the New Testament (which did not include the book of Revelation) which dated from the 15th Century (x2) and 12th Century (x5).  With these he composed his "Novum Instrumentu" (New Testament). While Martin Luther was sequestered in Wartburg Castle in Eisenach, Germany(1521-1522), he took a copy of Erasmus's 3rd Edition Greek New Testament and translated it into the German language.  Of note, Erasmus's Greek New Testament was used as the basis of translation of the 1611 King James Bible (along with comparisons to the works of the English translations of Wycliffe, Tyndale and Coverdale).  (resource: How We Got the Bible by Neil Lightfoot)