  Clifford algebras and Majorana conditions are analyzed in any spacetime. An
index labeling inequivalent $\Gamma$-structures up to orthogonal conjugations
is introduced. Inequivalent charge-operators in even-dimensions, invariant
under Wick rotations, are considered. The hermiticity condition on free-spinors
lagrangians is presented. The constraints put by the Majorana condition on the
free-spinors dynamics are analyzed. Tables specifying which spacetimes admit
lagrangians with non-vanishing kinetic, massive or pseudomassive terms (for
both charge-operators in even dimensions) are given. The admissible free
lagrangians for free Majorana-Weyl spinors are fully classified.
