Season 4

Season 4 of premiered on October 4, 1999  on PBS. This was the first season in which only 10 episodes (20 segments) were produced per season, a pattern that would not be broken until Season 20.

This is the first season to feature voice actor Oliver Grainger as D.W. This is also the very final season to feature Luke Reid's voice of The Brain. This is the second to last season to have Michael Yarmush as the voice of Arthur, as he would continue voicing him up to the next season. Head writers Joe Fallon and Ken Scarborough also left the team after this season, though Scarborough would return as a writer starting in Season 9.