Rapidly spinning, strongly magnetized neutron stars ("millisecond magnetars") are candidate engines for powering a wide range of astrophysical transients, including superluminous supernovae (SLSNe), long duration gamma-ray bursts (GRB), and fast radio bursts (FRB).  I will overview a unified magnetar model for SLSNe/GRBs/FRB.  Possible topics of discussion include (1) how the non-thermal radiation from the magnetar-inflated nebula is thermalized by the surrounding ejecta; (2) early maxima in SLSN light curves due to the emergence of a shock driven through the ejecta by the magnetar-inflated bubble or an off-axis relativistic jet; (3) the impact of fall-back accretion on the spin-down properties of the magnetar and SLSN light curves.