Let Xr be the moduli space
of SLn, SUn, GLn, or Un -valued representations of a rank r free group. We classify the
algebraic singular stratification of Xr. This comes down to showing that the singular
locus corresponds exactly to reducible representations if there exist singularities at
all. Then by relating algebraic singularities to topological singularities, we show the
moduli spaces Xr generally are not topological manifolds, except for a few examples
we explicitly describe.