Killjoy

Killjoys are characters who deliberately spoil the enjoyment of others through resentful or overly sober behavior.

A few examples include

Mr.Krabs- He often ruins things for others by being very cheap and doesn't seem to care about how other enjoy things unless it affects his money.

Circus Baby- She often torments others often replacing their enjoyment with fear.

The backrooms- It often scares people by trapping them inside of it and never gives them joy but rather hatred, sadness or fear.

William Afton(Killer in purple)- He often torments others and kills people for fun making him nothing more than the ultimate Killjoy.

Dio Brando- Dio often torments others or forces them to do his bidding or manipulate them. This can ruin other people's lives or take the joy out of it entirely making a perfect example of a kill joy.

Squidward- Squidward is often seen as a "Party popper" due to him not wanting to participate in the activities that Spongebob & Partick do. Sometimes he even goes out of his way to make sure they don't have fun making him a great example of a killjoy.