Sub-franchises: Dragon Quest Monsters | Dragon Quest Heroes
Related franchises: Final Fantasy | Itadaki Street | Mystery Dungeon
The series has become so popular in Japan, that a rumor has stated that the games were only released on weekends in Japan, because mid-week launches would see thousands of people calling in sick to go play it.
For releases in the Dragon Quest franchise that were released in the US, they were required to be re-branded Dragon Warrior. This was because there was a pen & paper RPG called DragonQuest that held the trademark. However, in 2003, Wizards of the Coast who owned the DragonQuest game abandoned the trademark and Square Enix picked it up. Dragon Quest VIII was the first game to carry the Dragon Quest name in the US, and all releases since then have also carried the Dragon Quest name in the US.