  In this short paper, we study Majorana fermions in terms of a modified
Chandrasekhar's separation for the Dirac equation in Kerr-Newman-type
spacetimes. If the electric charge or magnetic charge is nonzero, we show that
nontrivial differentiable time-periodic Majorana fermions do not exist outside
the event horizon in Kerr-Newman and Kerr-Newman-AdS spacetimes, and between
the event horizon and the cosmological horizon in Kerr-Newman-dS spacetime.
