(Serious) favorite depiction of an alien, or aliens? I’ll go first (some spoilers for IT by Stephen King)

IT, from the Stephen King novel of the same name. It is an inter-dimensional entity that feeds on human fear and changes shape depending on who it is preying on, but its go-to shape is Pennywise the clown. Its true form is an incomprehensible entity beyond human understanding, called the deadlights.