  Using resolved stellar photometry measured from archival HST imaging, we
generate color-magnitude diagrams of the stars within 50 pc of the locations of
historic core-collapse supernovae that took place in galaxies within 8 Mpc. We
fit these color-magnitude distributions with stellar evolution models to
determine the best-fit age distribution of the young population. We then
translate these age distributions into probability distributions for the
progenitor mass of each SNe. The measurements are anchored by the main-sequence
stars surrounding the event, making them less sensitive to assumptions about
binarity, post-main-sequence evolution, or circumstellar dust. We demonstrate
that, in cases where the literature contains masses that have been measured
from direct imaging, our measurements are consistent with (but less precise
than) these measurements. Using this technique, we constrain the progenitor
masses of 17 historic SNe, 11 of which have no previous estimates from direct
imaging. Our measurements still allow the possibility that all SNe progenitor
masses are <20 M_sun. However, the large uncertainties for the highest-mass
progenitors also allow the possibility of no upper-mass cutoff.
