My 2yo had started complaining of monsters in her room when she's put down for naps/bedtime & when she wakes up.
She's still going down ok... so not a huge issue. I'm just a bit unsure of what tack to take.. i.e. Don't worry monsters are fun to pretend but there not real, don't worry etc, or oh hello me friendly monster come play downstairs with me etc. We've kinda done a mish mash of the two, so I'm sure she's confused!