It’s also just two words. Spanish worlds tend to be longer than english ones.
“Muertos” is a direct translation of “dead”.
“Evil” would be “maligno”, but “terroríficamente” was used "which would be like “terrifying”.
Anyway spanish translations used to change a lot the titles of the movies back in the day, most famously “die hard” is “la jungla de cristal” (directly translated as: the glass jungle) here.
I’ve heard that they did this because direct translations or english titles didn’t work as well here, and a change in the title made more people want to watch the movie.
Nowadays this happens way less, most titles are direct translations or use their english title directly.
I’m from Spain.
But I know that in Latin America they also used to change the title of some media sometimes. Funny enough they used different titles than in Spain.
For instance, the movie “White Chicks” in Spain is “Dos rubias de pelo en pecho” and in Latin America is “¿Y donde están las rubias?”.