  M71E is a spider pulsar (i.e., a millisecond pulsar with a tight binary
companion) with the shortest known orbital period of P=53.3 min discovered by
Pan et al. (2023). Their favored evolutionary model suggests that it bridges
between two types of spider pulsars, namely, it descended from a "redback" and
will become a "black widow". Using Hubble Space Telescope (HST) archival
imaging data, we report the first optical identification of its companion
COM-M71E. The HST and pulsar timing coordinates are in excellent agreement
(within ~10 mas). If M71E is associated with the globular cluster M71, our
measured brightness of COM-M71E (m_F606W ~ 25.3) is broadly consistent with the
expectation from Pan et al. (2023)'s preferred binary evolutionary model of a
stripped dwarf companion, while it is also compatible with an ultra-low-mass
degenerate companion. Future multi-wavelength photometric and spectroscopic
observations can characterize the companion and test the evolutionary
scenarios.
