This paper deals with the existence of assembles of an arbitrary number of complex oscillators, or equivalently of an arbitrary even number of real oscillators, characterized by Newtonian equations of motion (“acceleration equal force”) with one-body velocity-dependent linear forces and many-body velocity-independent cubic forms, all the nonsingular solutions of which are isochronous. As for the singular solutions, as usual they emerge, in the context of the initial-value problem, from a closed domain in phase space having lower dimensionality.