  We performed deep photometry of the central region of Galactic globular
cluster M15 from archival Hubble Space Telescope data taken on the High
Resolution Channel and Solar Blind Channel of the Advanced Camera for Surveys.
Our data set consists of images in far-UV (FUV$_{140}$; F140LP), near-UV
(NUV$_{220}$; F220W), and blue (B$_{435}$; F435W) filters. The addition of an
optical filter complements previous UV work on M15 by providing an additional
constraint on the UV-bright stellar populations. Using color-magnitude diagrams
(CMDs) we identified several populations that arise from non-canonical
evolution including candidate blue stragglers, extreme horizontal branch stars,
blue hook stars (BHks), cataclysmic variables (CVs), and helium-core white
dwarfs (He WDs). Due to preliminary identification of several He WD and BHk
candidates, we add M15 as a cluster containing a He WD sequence and suggest it
be included among clusters with a BHk population.
  We also investigated a subset of CV candidates that appear in the gap between
the main sequence (MS) and WDs in FUV$_{140}-$NUV$_{220}$ but lie securely on
the MS in NUV$_{220}-$B$_{435}$. These stars may represent a magnetic CV or
detached WD-MS binary population. Additionally, we analyze our candidate He WDs
using model cooling sequences to estimate their masses and ages and investigate
the plausibility of thin vs. thick hydrogen envelopes. Finally, we identify a
class of UV-bright stars that lie between the horizontal branch and WD cooling
sequences, a location not usually populated on cluster CMDs. We conclude these
stars may be young, low-mass He WDs.
