A quick wikipedia research gave me a list of Anglo-Saxon God's, but because HTML is off I can't post the handy table that is given on that site, showing the Anglo - Saxon, then the Old German and then the Norse equevelant.
But
http://en.wikipedia.org/wiki/Anglo-Saxon_deities is the link to the Wikipedia article. This learn's us that, Týr being, in later Norse Mythology playing a Mars-like Role, is the equivalent of Tíw. (Or Zîu in Old German).
Since I havn't learned of one Germanic language where the Genitive case isn't an S for male singular, Tíws would be the equivalent of Martis.
(If Anglo-Saxon is different with the s from Dutch, German, Old Norse (and the 6 language's derived from Old Norse) and Modern English, please do tell)