I am happy as a peacock to report that Mexico does not have much in the way of Creepy Dangerous Things that come out in the night to do you in while you sleep.
There are, however, some things that can give one pause. Unlike Australia where there are many things to bite you, sting you, poke you, and generally make you die as the result of your encounter with them, Mexico is relatively safe. Mexico does have a few things that you probably do not want to encounter on a regular basis.
Mexico has two lizards which are kissing cousins, The Gila monster (Heloderma suspectrum) and The Mexican beaded lizard (Heloderma horridum). The Gila monster (take careful note of the word, monster) lives in the desert regions of Mexico. The Mexican beaded lizard (Heloderma horridum)horridum as in HORRORis found from Mexico to South America. Both of these, while poisonous, are docile and do not seek you out to kill you.
Many years ago when I was a college student, a student in one of the dorms kept one of these hideous lizards in his room in a fish tank. When his roommate would go home for the weekend, he would take his poisonous pet out of the tank and let it loose in the room...