2026-07-072026-07-07http://salesiana.dossiersoluciones.com/handle/123456789/211123We review some theoretical and phenomenological aspects of massive gravities in 4 dimensions. We start from the Fierz--Pauli theory with Lorentz-invariant mass terms and then proceed to Lorentz-violating masses. Unlike the former theory, some models with Lorentz-violation have no pathologies in the spectrum in flat and nearly flat backgrounds and lead to interesting phenomenology.81 page, 2 postscript figuresHigh Energy Physics - Theorytext