  It is well known that almost all isolated dwarf galaxies are actively forming
stars. We report the discovery of Hedgehog, an isolated quiescent dwarf galaxy
at a distance of $2.41\pm0.14$ Mpc with a stellar mass of $M_\star \approx
10^{5.8}\, M_\odot$. The distance is measured using surface brightness
fluctuations with both Legacy Surveys and deep Magellan/IMACS imaging data.
Hedgehog is 1.7 Mpc from the nearest galaxy group, Centaurus A, and has no
neighboring galaxies within 1 Mpc, making it one of the most isolated quiescent
dwarfs at this stellar mass. It has a red optical color, early-type morphology,
and shows no UV emission. This indicates that Hedgehog has an old stellar
population and is quiescent in star formation. Compared with other quiescent
dwarfs in the Local Group and Local Volume, Hedgehog appears smaller in size
for its luminosity but is consistent with the mass--size relations. Hedgehog
might be a backsplash galaxy from the Centaurus A group, but it could also have
been quenched in the field by ram pressure stripping in the cosmic web,
reionization, or internal processes such as supernova and stellar feedback.
Future observations are needed to fully unveil its formation, history, and
quenching mechanisms.
