I would kill a million for a reason, but I wouldn't kill even one for no reason.
~ The High Gul, explaining he would not kill unless necessary.

The High Gul was a Cardassian male who had lived during the 23rd and 24th century. High Gul was his title, his full name was unknown.

In the 23rd century the man who eventually became known as the High Gul rose to the leadership of the Crescent Order, one of the most respected orders in Cardassian society. Upon assuming leadership he was named High Gul, and became the only Cardassian to receive that rank.

Sometime in the late 23rd century the High Gul and nearly 3,000 of his best troops were put into suspended animation. The plan had originally been that they would be revived at an opportune time to attack an unspecified enemy.

However a young man named Fransu murdered nearly all of the High Gul's troops. Fransu hid the bodies of the High Gul and several of his top soldiers for a number of years, and placed them in a vacuum sealed chamber on what would later become Deep Space Nine. The High Gul and his aides were quickly forgotten about, and the corridor leading up to the chamber eventually collapsed in upon itself.

In 2371 the chamber where the High Gul and his remaining soldiers were being held was accidentally broken in to Chief O'Brien and Odo while reviewing collapsed tunnels on the station. Assuming all the Cardassians inside were quite dead, Captain Benjamin Sisko brought Elim Garak in to ask what should be done. After everyone had left Garak returned to the tunnel and revived the High Gul and his men.

After awakening the High Gul tried to take over the station. He and his men killed several of the security forces and managed to temporarily incapacitate Odo by firing gaseous explosives into his body, which would cause him to explode if he changed shape. (The gas was later filtered out of Odo's body).

Meanwhile Fransu, by now a Gul himself, had discovered the High Gul and his men had been arrived. He took his ship Rugg'l to DS9 in order to kill High Gul and his men, and was also going to destroy the station to silence any witnesses.

When Fransu started attacking DS9, the High Gul joined forces with Sisko and Major Kira to defeat Fransu. The three were able to finally defeat Fransu. Fransu then revealed to the High Gul that his wife had survived all the years he had been in stasis, and was on the Rugg'l. When Fransu attempted to use her as a hostage, the High Gul's wife told her husband that she had lived long enough. The High Gul activated the Defiant's weapons while Fransu retaliated by slitting the throat of the High Gul's wife.

Fransu was taken prisoner by the Federation starships sent to assist the DS9 crew. Realizing that modern Cardassia would tear itself apart no matter what happened to him, the High Gul turned on the Defiant's bridge recorders just before he vaporized himself with a Starfleet hand phaser.