  Supernova (SN) 2004et is the eighth historical SN in the nearby spiral galaxy
NGC 6946. Here we report on early photometric and spectroscopic monitoring of
this object. SN 2004et is a Type II event, exhibiting a plateau in its light
curves, but its spectral and color evolution appear to differ significantly
from those of other, more normal Type II-plateau (II-P) SNe. We have analyzed
Canada-France-Hawaii Telescope (CFHT) images of the host galaxy taken prior to
the SN explosion, identifying a candidate progenitor for the SN. The star's
absolute magnitude and intrinsic color imply that it was a yellow, rather than
red, supergiant star, with an estimated zero-age main sequence mass of
$15^{+5}_{-2} M_\odot$. Although this mass estimate is consistent with
estimates and upper limits for the progenitors of other, more normal SNe II-P,
the SN 2004et progenitor's unusual color could further imply a pre-explosion
evolutionary history analogous to, but less extreme than, that for the
progenitors of the peculiar Type II-P SN 1987A or the Type IIb SN 1993J. The
identity of the progenitor candidate needs to be verified when the SN has
significantly dimmed.
