Seasons

There are four seasons of Regular Show

Season One
Season One consisted of 12 episodes and started on September 6, 2010 with The Power. It ended in early December 2010 with Mordecai and the Rigbys. There were no deleted episodes, though there was some deleted media from the last episode, listed above.

Season Two
Season Two consisted of 36 episodes. It started in late December 2010, soon after the season finale of season one, with Ello Gov'nor. The season ended in early August 2011 with Karaoke Video. Like the first season, there is no deleted episodes, though some deleted media was in the last episode, listed above.

Season Three
Season Three will consist of 40 episodes. It started on September 19, 2011 and is still airing new episodes, taking a break in December 2011 to the middle of January 2012. As of now, there is no deleted episodes or media. The season is supposed to end in August 2012, according to Benton Connor in a post on Formspring.me.

Season Four
Season Four was confirmed by Calvin Wong on his Formspring.me to be official. The first episode is currently being written by Benton Connor and Calvin Wong, but the title is unknown. As of many rumors, Wong confirmed that Parental Controls was a mistakingly made episodes on the website, as they meant "parental controls" to block the show, not for an episode.

Trivia

 * There is 85 episodes total as of now, counting the season four pilot.