Gul Dukat is a major antagonist in Star Trek Deep Space Nine and is a high-ranking member of the Cardassian race (Gul is actually a title rather than part of his true name).
However like many antagonistic forces in Star Trek Dukat is not fully evil and will aid the protagonists on occassions, making him somewhat of a wildcard who can be an enemy one minute and an ally the next.
One of Dukat's first assignments was as a newly-minted glinn aboard the Kornaire. Among his tasks as a glinn was cleaning out a compartment where three men had gone through an explosive decompression, after which he could not sleep for a week. At some point prior to being stationed on Bajor, Dukat was a legate, but he lost favor with Cardassian Central Command and was reduced to the rank of Gul. He later rejected the title of legate because he felt Gul was more "hands on".
Prefect of Bajor
By 2346, at the rank of gul, Dukat was made Prefect of Bajor. In 2360 he was assigned command of Terok Nor, the mining station and command post in orbit of Bajor that was later known as Deep Space 9. Dukat was the last Prefect of Bajor before the end of the Occupation. He was responsible for many atrocities committed against the Bajoran people, and became one of the most hated individuals in Bajoran history.
According to Dukat, he was convinced that a gentler approach was needed to quell the Bajoran Resistance and make Bajor suitable for colonization. His first act as prefect was to cut labor camp output quotas by fifty percent, abolish child labor, and improve medical care and food rations. These measures led to a twenty percent drop in the camp death rates. However, the Resistance repaid him by destroying an orbital drydock on his one-month anniversary, killing two hundred Cardassians. During the Occupation, the Resistance attempted to assassinate Dukat five times, all of them unsuccessful. Dukat grew to hate the Bajorans for not acknowledging his "compassion" towards them.
Despite his professed hatred for his charges, he conducted numerous affairs with Bajoran women, including Kira Meru, mother of Kira Nerys, and Tora Naprem, whom he claimed to love, and with whom he fathered a daughter, Tora Ziyal.
While prefect, Dukat reported to Legate Kell regularly; however, he did not have the respect from Kell that he was led to believe. Dukat created a counter-insurgency program to combat potential worker revolts on Terok Nor, but Kell secretly added a level to it in case Dukat tried to flee. The automated program was set to deal with various situations, the most severe of which was a complete takeover of the station. In the event that this happened, the program could initiate an auto-destruct sequence, and if Dukat tried to transport off the station while this sequence was in effect, his access codes would be nullified and he would be doomed to die with his station.
Dukat strongly opposed the Cardassian withdrawal from Bajor in 2369, a move which damaged his career as it occurred during his administration. After the withdrawal, Dukat became the commander of the Second Order. He played a major role in many interactions between the Cardassian military and the Federation for the next three years, and made several visits to his former command post, Deep Space 9, under various circumstances.
Dukat was implicated in the supplying of illegal weapons to Cardassian citizens in the Demilitarized Zone in 2370 by his political enemies, including Legate Parn. Dukat assisted Commander Benjamin Sisko in his investigation of the Maquis, so as to prove his innocence. He was briefly abducted by the Maquis, but he was rescued by Sisko. It emerged that the Cardassian Central Command was actually responsible for violating the Federation-Cardassian Treaty.
When the Cardassian Union underwent a revolution in 2372, Dukat sided with the victorious Detapa Council. He was promoted to Legate, and was made chief military adviser. Following the Klingon invasion of the Union, Dukat was able to evacuate the Council members to Federation space aboard the cruiser Prakesh, with the timely assistance of the USS Defiant.
Later that year, Dukat accompanied Kira Nerys to Dozaria to find the wreck of the Ravinok, a transport that had been lost several years earlier with Dukat's mistress, Tora Naprem, and his half-Bajoran daughter, Tora Ziyal, aboard. Dukat had initially intended to kill both Ziyal and Naprem, had they survived. However, after he found his daughter alive, he decided to take her with him back to Cardassia, despite the effect it would have on his career.
Fighting the Klingons
After he returned with Ziyal, Dukat was demoted and given command of a small freighter, the Groumall. His family disowned him, his wife and children left him, and both he and Ziyal were shunned by Cardassian society. The Groumall transported Kira to the outpost at Korma in 2372. After finding the outpost destroyed, Dukat and Kira were able to capture the Klingon Bird-of-Prey responsible. Dukat urged the Detapa Council to use his captured intelligence to mount a new offensive against the Klingons, but they rejected his proposal, preferring to seek a diplomatic option.
Disgusted with the Council's unwillingness to fight, Dukat began to carry on his own one-ship war against the Klingons. In 2373, he and his ship helped an undercover Starfleet team, led by Sisko, infiltrate Klingon military headquarters on Ty'Gokor to expose a Changeling.
Alliance with the Dominion
By 2373, Dukat became convinced that the only way to regain Cardassia's former glory was for them to join the Dominion. In secret talks, he negotiated Cardassia's entry into the Dominion with himself as ruler. Dukat promised to the Cardassian people that under his leadership, all that Cardassia lost would be regained. His move was initially celebrated by most Cardassians, who had suffered defeat and humiliation for years at the hands of the Federation and Klingons. Dukat chose not to promote himself back to legate, since he saw the rank of gul as more "hands-on". One of Dukat's first acts was to have his Dominion allies release all surviving Cardassians from Internment Camp 371 with one exception – Elim Garak, who had not only killed Dukat's father but had also fallen in love with Tora Ziyal.
In the months after his taking office, Dukat made good on his promises by expelling the Klingons from Cardassian space and wiping out the Maquis with his newly gained Dominion allies. Dukat commanded the Dominion forces which retook Terok Nor from the Federation in late 2373. In the following weeks, Dukat directed the Dominion War from his old command, winning many early victories against the Federation and the Klingon Empire. Bringing in Dominion reinforcements from the Gamma Quadrant by re-opening the Bajoran wormhole was to be his greatest triumph.
However, victory was snatched from his grasp when the Dominion reinforcements were eliminated by the Prophets. As allied forces retook the station during Operation Return, Dukat – driven half-mad by his rapid change of fortune – descended into insanity after the murder of his beloved daughter Ziyal by Damar, his second-in-command. He refused to evacuate with the rest of the Dominion forces, and was captured by Starfleet.
Afterward, Dukat began suffering from hallucinations and fits of paranoia, and was treated by Federation doctors. After he was declared "recovered", Dukat was to be taken to a Special Jury at Starbase 621 aboard the USS Honshu to stand trial for war crimes. However, the Honshu was intercepted by Cardassian warships, and Dukat escaped to a nearby planet in a shuttlecraft with his nemesis, Benjamin Sisko. Dukat's hallucinations returned, and he attempted to kill Sisko before escaping in the shuttle. During his time on the planet, Dukat embraced his hatred for the Bajoran people, promising to one day return and rain destruction on all of Bajor. Even more than before, his actions got increasingly proactively evil.
Pact with the Pah-wraiths
In late 2374, Dukat believed he had found a way to destroy the Bajoran people and their Emissary. Having immersed himself in the ancient Bajoran texts, he discovered that the wormhole was actually the Celestial Temple. He returned to Cardassia Prime and enacted an ancient Bajoran ritual to release a Pah-wraith into his body. Thus possessed, he traveled to Deep Space 9 and released it into the Celestial Temple via the Orb of Contemplation, causing the wormhole to disappear. In the process, Dukat killed Jadzia Dax, who was simply in his way.
His inhabitation by the Pah-wraith had turned Dukat into their believer; subsequently he retreated to station Empok Nor and founded a community of members from the Cult of the Pah-wraiths. He was worshiped as a messiah, and fathered another half-Bajoran child with Mika. Dukat never publicly admitted fatherhood. Dukat attempted to have the cult members commit suicide to conceal his attempt to kill Mika. When he was exposed, he fled again.
In late 2375, Dukat secretly underwent cosmetic surgery on Cardassia Prime to pose as a Bajoran farmer, Anjohl Tennan. He then traveled to Deep Space 9 and gained the confidence of Kai Winn Adami and even became romantically involved with her - albeit for ulterior motives - and with the assistance of false visions given to Winn by the Pah-wraiths, he slowly convinced her to join him as a follower of the Pah-wraiths. The two plotted to release the Pah-wraiths from their prison in the Fire Caves, using the Book of the Kosst Amojan.
The pair entered the Fire Caves, where Winn poisoned Dukat as a sacrifice to complete the release ritual. However, the Pah-wraiths rejected Winn and chose Dukat as their Emissary, restoring him to life and imbuing him with their power. After Dukat killed Winn, Sisko plunged himself and Dukat into the fires, which destroyed the book and trapped Dukat forever in the prison with the Pah-wraiths. Sisko himself was rescued by the Prophets.