Parodied: A scientist undergoes a lab accident, turns into a monster, and spotaneously decides to strip to nothing but underwear "because that's what monsters wear".
Zig Zagged: A monster wears normal clothes and even suits like a normal person but strips down when going into battle because it helps mobility. Besides, he's Made of Iron anyway so it's not like he needs protection.
Averted: A monster is so horrified with his appearance that he walks around in a full body costume and mask.
Enforced: "Sure, it would be more realistic if the monster just bursted out of his clothes, and started wreaking havoc while wearing nothing at all! ...However, our censors wouldn't allow that because children are our target demographic". note "...But maybe we could do that in the Darker and Edgier reboot".
Lampshaded: "Hey, is that monster wearing underwear? How did he find underwear that big? Did he buy it? If so, how? Also, if he cares enough to have underwear, why not put more clothes on?"
Invoked: A normal human gets transformed into a monster and designs a costume for himself, consisting of not much.
Exploited: The monster is a hot woman who only vaguely looks inhuman. Everything else is Fanservice that she actively employs to deal with her enemies and other annoying individuals.
Defied: A monster is actually modest and can't fathom the idea of not wearing clothes.
Discussed: Bob and Alice are reading a comic and discuss how silly this trope is after seeing a creature wearing undies.
Implied: A monster is never fully seen because Nothing Is Scarier but one character does give a brief description: "It was horrible! It was big, ugly, and might've been wearing scraps of clothing. It was hard ot tell."
Deconstructed: The monster questions his choice of attire, realizing that there is no practical purpose...
Reconstructed: ... Then again, a monster would look pretty silly in a full suit. He decides to stick with what he has.
Played For Laughs: A monster walks around in pink boxer shorts with little hearts on them.
Played For Drama: A monster has Abusive Parents who treated him like an animal, thus, he lived his entire life with only shreds to wear, never fully realizing the concept of clothes.