  The number of four-body states known to behave universally is small. This
work adds a new class of four-body states to this relatively short list. We
predict the existence of a universal four-body bound state for heavy-light
mixtures consisting of three identical heavy fermions and a fourth
distinguishable lighter particle with mass ratio $\kappa \gtrsim 9.5$ and
short-range interspecies interaction characterized by a positive s-wave
scattering length. The structural properties of these universal states are
discussed and finite-range effects are analyzed. The bound states can be
experimentally realized and probed utilizing ultracold atom mixtures.
