The Clock is a minor imaginary friend who only appeared in the series finale, Goodbye to Bloo. Clock goes through the halls every hour, on the hour, announcing the current time and stating whether or not things were going smoothly.
At the beginning of Goodbye to Bloo, Bloo is seen waiting outside for Mac to show up, when Clock walks into the foyer announcing that it was 4:00 and that all was well. Bloo immediately tackled him and explained the deal that Mac made with Madame Foster, which stated that as long as Mac came to visit everyday by three, Bloo wouldn't get adopted, and if Mr. Herriman heard that it was past three, Bloo would get adopted. Clock explained that Herriman already knew and that he had overhead him on the phone with Mac.
Several more times during the episode, he was seen walking through the halls every hour announcing the time and stating whether all was well. He made his final appearance at Mac's going away party, stating that it was 6:00 and that all was not well.