  We have studied the half-Heusler compound TbPdBi through resistivity,
magnetization, Hall effect and heat capacity measurements. A semimetal behavior
is observed in its normal state transport properties, which is characterized by
a large negative magnetoresistance below 100 K. Notably, we find the
coexistence of superconductivity and antiferromagnetism in this compound. The
superconducting transition appears at 1.7 K, while the antiferromagnetic phase
transition takes place at 5.5 K. The upper critical field $H_{c2}$ shows an
unusual linear temperature dependence, implying unconventional
superconductivity. Moreover, when the superconductivity is suppressed by
magnetic field, its resistivity shows plateau behavior, a signature often seen
in topological insulators/semimetals. These findings establish TbPdBi as a
platform for study of the interplay between superconductivity, magnetism and
non-trivial band topology.
