spoilsport

/ˈspɔɪlspɔrt/
noun
  1. A person who spoils the enjoyment or fun of others, especially by refusing to join in or by being overly cautious or negative.
    • He was called a spoilsport for reminding everyone about the rules during the party.
    • Don't be a spoilsport — come join us for the game!
    • The teacher felt like a spoilsport when she had to cancel the field trip due to bad weather.
Antonyms