  We deal with Lagrangians which are not the standard scalar ones. We present a
short review of tensor Lagrangians, which generate massless free fields and the
Dirac field, as well as vector and pseudovector Lagrangians for the electric
and magnetic fields of Maxwell's equations with sources. We introduce and
analyse Lagrangians which are equivalent to the Hamilton-Jacobi equation and
recast them to relativistic equations.
