die Bestie

1. 1

   a very cruel person, a monster, fiend — usually a killer, torturer, or rapist

2. 2

   a wild and very dangerous animal, a beast, monster

   • Das liegt in der Natur der Bestie.

     That's the nature of the beast.

     Tatoeba · al_ex_an_der · CC BY 2.0 FR

Forms in lighter type are derived by the standard declension rules from the nominative, genitive and plural.