  The tight correlations between the mass of supermassive black holes ($M_{\rm
BH}$) and their host-galaxy properties have been of great interest to the
astrophysical community, but a clear understanding of their origin and
fundamental drivers still eludes us. The local relations for active galaxies
are interesting in their own right and form the foundation for any evolutionary
study over cosmic time. We present Hubble Space Telescope optical imaging of a
sample of 66 local active galactic nuclei (AGNs); for 14 objects, we also
obtained Gemini near-infrared images. We use state-of-the-art methods to
perform surface photometry of the AGN host galaxies, decomposing them in
spheroid, disk and bar (when present) and inferring the luminosity and stellar
mass of the components. We combine this information with spatially-resolved
kinematics obtained at the Keck Telescopes to study the correlations between
$M_{\rm BH}$ (determined from single-epoch virial estimators) and host galaxy
properties. Our sample extends the correlation found for quiescent galaxies
down to $M_{\rm BH}$ $\sim$ $10^7$ $M_{\odot}$ along a consistent line. The
correlations are uniformly tight for our AGN sample, with intrinsic scatter
0.2-0.4 dex, smaller or equal to that of quiescent galaxies. We find no
difference between pseudo and classical bulges or barred and non-barred
galaxies. We show that all the tight correlations can be simultaneously
satisfied by AGN hosts in the $10^7-10^9$ $M_{\odot}$ regime, with data of
sufficient quality. The $M_{\rm BH}$-$\sigma$ relation is also in excellent
agreement with that of AGN with $M_{\rm BH}$ obtained from reverberation
mapping, providing an indirect validation of single-epoch virial estimators of
$M_{\rm BH}$.
