  The phase structure of QCD with various number of flavors is studied for
Wilson quarks. For the case of $N_F=3$ we find that the finite temperature
deconfining transition is of first order in the chiral limit on an $N_t=4$
lattice. Together with our previous results that the deconfining transition in
the chiral limit is continuous for $N_F=2$ and is first order for $N_F=6$, the
order of the transition is found to be consistent with a prediction of
universality. The case of $SU(2)$ QCD is also studied in the strong coupling
limit and the phase structure is found to be quite similar to the case of
$SU(3)$: There exists a critical number of flavors $N_F^*$ and for $N_F \geq
N_F^*$ the confinement is broken even in the strong coupling limit for light
quarks. $N_F^*=3$ corresponding to 7 for $SU(3)$.
