  I briefly describe the Lick Observatory Supernova Search with the 0.76-m
Katzman Automatic Imaging Telescope. I then present an overview of optical
observations of Type II, IIb, Ib, and Ic supernovae (SNe), all of which are
thought to arise from core collapse in massive progenitors that have previously
experienced different amounts of mass loss. SNe IIn are distinguished by
relatively narrow emission lines with little or no P-Cygni absorption
component; they probably have unusually dense circumstellar gas with which the
ejecta interact. Some SNe IIn, however, might actually be super-outbursts of
luminous variable stars; rarely, they may even be SNe Ia in disguise. Plausible
detections of the progenitors of a few SNe II have been made.
Spectropolarimetry of core-collapse SNe reveals that asphericity increases
toward the core.
