Non-Lie integrals of the motion for particles of arbitrary spin and for systems of interacting particles

New integrals of the motion are found for the Kemmer–Duffin–Petiau, Rarita–Schwinger, Dirac–Fierz–Pauli, and Bhabha equations describing minimal and anomalous coupling of particles of spin $s\leqslant 2$ with the field of a point charge and also for a number of relativistic and quasirelativistic two- and three-particle equations. These integrals belong to the class of differential operators of order $2s$ with matrix coefficients and have a discrete spectrum.