  The core collapse of rapidly rotating massive ~10 Msun stars ("collapsars"),
and resulting formation of hyper-accreting black holes, are a leading model for
the central engines of long-duration gamma-ray bursts (GRB) and promising
sources of r-process nucleosynthesis. Here, we explore the signatures of
collapsars from progenitors with extremely massive helium cores >130 Msun above
the pair-instability mass gap. While rapid collapse to a black hole likely
precludes a prompt explosion in these systems, we demonstrate that disk
outflows can generate a large quantity (up to >50 Msun) of ejecta, comprised of
>5-10 Msun in r-process elements and ~0.1-1 Msun of $^{56}$Ni, expanding at
velocities ~0.1c. Radioactive heating of the disk-wind ejecta powers an
optical/infrared transient, with a characteristic luminosity $\sim 10^{42}$ erg
s$^{-1}$ and spectral peak in the near-infrared (due to the high optical/UV
opacities of lanthanide elements) similar to kilonovae from neutron star
mergers, but with longer durations $\gtrsim$ 1 month. These "super-kilonovae"
(superKNe) herald the birth of massive black holes >60 Msun, which, as a result
of disk wind mass-loss, can populate the pair-instability mass gap 'from above'
and could potentially create the binary components of GW190521. SuperKNe could
be discovered via wide-field surveys such as those planned with the Roman Space
Telescope or via late-time infrared follow-up observations of extremely
energetic GRBs. Gravitational waves of frequency ~0.1-50 Hz from
non-axisymmetric instabilities in self-gravitating massive collapsar disks are
potentially detectable by proposed third-generation intermediate and
high-frequency observatories at distances up to hundreds of Mpc; in contrast to
the "chirp" from binary mergers, the collapsar gravitational-wave signal
decreases in frequency as the disk radius grows ("sad trombone").
