There are four artists sharing the name Killjoy.

1: Killjoy are a heavy-metal band hailing from Ruda Śląska, Poland, consisting of Wojtek Bujoczek (vocals), Marek Ludwicki (lead guitar), Adam Rogowicz (rhythm guitar), Wojtek Gajda (bass) and Marcin Bruner (drums). Founded in 1993 under the name Mystic Side as a thrash-metal band, it was renamed to Killjoy in 1998. At first the band was intended to play a lighter kind of music, but soon they turned back to a heavier sound.

The band recorded a couple of demos, including ...a drug called reality and Back To The Past. The year 2005 saw the signing of a contract with Shark Records and the release of their debut album - Enemigo.

Some of band's work can be downloaded from their website

2: The other artist is a single person who plays in such bands as Necrophagia and Viking Crown.

3:
The third one was an old Hardcore/Punk band from California which was featured on the "Not so quiet on the Western Front" Sampler LP.

4: the fourth artist known as killjoy is a breakcore producer from newcastle, australia. he is also tagged under variations of the name i.e. kill/joy, kill joy, kill_joy and kill//joy due to the unorganised nature of the kind of tards that are into breakcore.