noun. One who mars the pleasure of others.

noun. Someone who puts an end to other's fun, especially harmless fun.

noun. someone who spoils the pleasure of others

"It was to 'spoil the fun' for the last time as Gandhi failed to play 'spoilsport' ever again and the tournament continued until before partition."

burst someone’s bubble  bust someone’s bubble  buzz kill  killjoy  make waves  

persona non grata  unwelcome person  

fussbudget  fusspot  worrier  worrywart  

4-4-2  IRAS  Satanism  automake  candybar  

party pooper