Top Quark Mass Measurement at the Tevatron

We report on the latest experimental measurements of the top quark mass by the CDF and DØ Collaborations at the Fermilab Tevatron. We present a new top mass measurement using the tbar {t} events collected by the DØ Collaboration in Run I between 1994 and 1996. This result is combined with previous measurements to yield a new world top mass average. We also describe several preliminary results using up to 193 pb^-1 of tbar {t} events produced in bar {p}p collisions at √ {s} = 1.96 TeV during the Run II of the Tevatron.