  The Keplerian rotation in protoplanetary disks can be used to robustly
measure stellar masses at very high precision if the source distance is known.
We present Atacama Large Millimeter/submillimeter Array (ALMA) observations of
spatially and spectrally resolved $^{12}$CO (2--1) emission towards the disks
around 2MASS J16262774--2527247 (the tertiary companion to ROXs 12 at 5100 au),
CT Cha, and DH Tau. We employ detailed modeling of the Keplerian rotation
profile, coupled with accurate distances from $Gaia$, to directly measure the
stellar masses with $\sim$2\% precision. We also compare these direct mass
measurements with the masses inferred from evolutionary models, determined in a
statistically rigorous way. We find that 2MASS J16262774--2527247 has a mass of
$0.535^{+0.006}_{-0.007}~M_{\odot}$ and CT Cha has a mass of
$0.796^{+0.015}_{-0.014}~M_{\odot}$, broadly consistent with evolutionary
models, although potentially significant differences remain. DH Tau has a mass
of $0.101^{+0.004}_{-0.003}~M_{\odot}$, but it suffers from strong foreground
absorption that may affect our mass estimate. The combination of ALMA, $Gaia$,
and codes like \texttt{pdspy}, presented here, can be used to infer the
dynamical masses for large samples of young stars and substellar objects, and
place constraints on evolutionary models.
