What is Pennywise's true form in it?
				  
				  Pennywise's True Form in "It"
Pennywise the Dancing Clown is the most recognizable form of the entity in Stephen King's novel "It". However, this is merely a guise used to lure and terrify its prey. The true form of "It" is far more complex and otherworldly.
True Form in the Novel
  - Deadlights: The closest that humans can perceive of "It's" true form are the Deadlights, described as swirling, hypnotic, and incomprehensible lights. Looking directly at the Deadlights can drive a person insane or kill them instantly.
 
  - Interdimensional Being: "It" is revealed to be an ancient cosmic entity from a void known as the Macroverse (or "Todash Darkness"). Its true essence exists outside the physical realm and can’t be fully comprehended by humans.
 
Physical Manifestations
  - Spider-Like Creature: During the climax of the story, the Losers' Club perceives "It" as a gigantic spider-like monster, which is not its true form, but the closest thing their minds can process.
 
  - Shape-Shifter: "It" can shapeshift into whatever its victims fear most, using this ability to terrorize and feed on children in Derry.
 
Conclusion
Ultimately, Pennywise's true form is a cosmic, incomprehensible entity represented by the Deadlights. The clown and spider forms are only approximations that human minds can grasp.