(informal) someone who spoils the pleasure of others

• Defeat Johnson? Why? They say, he's a party pooper

WordNet Word definitions in WordNet
n. someone who spoils the pleasure of others [syn: spoilsport , wet blanket , party pooper ]

Wikipedia Word definitions in Wikipedia
Killjoy is a 2000 slasher film directed by Craig Ross, starring Ángel Vargas. Its sequel, Killjoy 2: Deliverance from Evil was released in 2002. A second sequel, Killjoy 3 was released in 2010, and Killjoy Goes to Hell in 2012.

Douglas Harper's Etymology Dictionary Word definitions in Douglas Harper's Etymology Dictionary
also kill-joy , 1776, from kill (v.) + joy . Formerly used with other stems (such as kill-courtesy "boorish person," kill-cow "bully, big man," etc.).

Wiktionary Word definitions in Wiktionary
n. A person who is anti-fun, or prevents others from having fun

Longman Dictionary of Contemporary English Word definitions in Longman Dictionary of Contemporary English
noun EXAMPLES FROM OTHER ENTRIES ▪ We wanted to do a sponsored dance after work but those killjoys in Head Office wouldn't let us.