PARADOX (PDX) is a well known warez/demo group that has cracked games and programs for Amiga, IBM PC, and numerous game consoles. It was founded in 1990. PARADOX began by cracking Amiga software. They moved on to the Sega Mega Drive and SNES in 1993, and started cracking PC software in 1994. Other consoles/handheld devices they cracked for include the PlayStation, PlayStation 2, Dreamcast, Nintendo 64, Game Boy, Microsoft Xbox and Sony PSP.  Paradox has been noted to crack challenging dongle protections and many debugging and software development programs.
They are also known for adding futuristic chiptunes to most of their keygenerators.
Their slogan is Mess with the Best, Die like the Rest!, which was also a quote from the film Hackers
SKIDROW is a well-known cracking group originally formed in 1990, cracking games for the Amiga platform, and having used the motto Twice the Fun - Double the Trouble! since then. A piece of cracktro software released by SKIDROW in 1992 with the game 10 Pinball Fantasies containing a complete list of their membership at the time.