Onizuka's favorite actress in the anime is Nanako Matsushima, who plays his love interest in the live-action drama version. Coincidentally, Matsushima is married to Takashi Sorimachi, who played Onizuka in that series.
This series only follow the manga starting from the 1st to the 13th volume, 106th chapter.
Starting around episode 28, Onizuka sometimes wears a T-shirt with the famous "Tongue and Lips Design" logo of the Rolling Stones.
This series is based on the popular Japanese manga with the same name that was serialized in Weekly Shonen Magazine from May 1997 to April 2002 by Tohru Fujisawa. It has 25 volumes.
The live action version of GTO is even more popular than both the anime and the manga.