(covers information from several alternate timelines)
"And absolute power corrupts absolutely."
In social and political science, power was the capacity of an individual to influence the actions, beliefs, or behavior of others.
In 1993, a group of young supermen seized power simultaneously in over forty Earth nations. (TOS: "Space Seed")
In 2258 of the alternate reality, upon James T. Kirk's awakening following a transfusion of Khan Noonien Singh's blood, Leonard McCoy questioned whether Kirk was feeling homicidal, power-mad or despotic. Kirk replied, "No more than usual." (Star Trek Into Darkness)
In 2259, the Vulcan Spock noted to the R'ongovian Brax that all members of the United Federation of Planets had a voice in its governance, which sounded confusing to Brax. Captain Vasso L'Gaelia asked how it was decided which voice was in control of the Federation when there were so many voices. Captain Christopher Pike responded that they vote, and that they gain their power from all their membership so they try to listen to each other. (SNW: "Spock Amok")
That same year, Hemmer (in the role of the magical wizard Caster) told Nyota Uhura (in the role of Queen Neve) to turn away or else he would unleash the full power of his powerful wizard powers. (SNW: "The Elysian Kingdom")
According to Spock in 2268, evil sought to maintain power by suppressing the truth. (TOS: "And the Children Shall Lead")
In 2285, Khan Noonien Singh noted that he was once a prince with power over millions on Earth. (Star Trek II: The Wrath of Khan)
In 2365, Q described the Borg as not being interested in power as the Federation knew it. (TNG: "Q Who")
In 2366, Jean-Luc Picard agreed with Data that terrorism could be an effective way to promote political change, but Picard never subscribed to the theory that political power came from the barrel of a gun. (TNG: "The High Ground")
In 2369, Deanna Troi assumed the identity of Rakal aboard the Romulan warbird Khazara and claimed that she had been given broad discretionary powers. (TNG: "Face Of The Enemy")
In 2370, Minister Jaro Essa told Winn Adami that he would do everything in his power to see Winn become the next kai. (DS9: "The Circle")
That same year, Major Kira Nerys obtained proof that Cardassians were behind Minister Jaro's attempt to take control of the Bajoran Provisional Government. Jaro responded that he had no intention of allowing Kira to disrupt the orderly transition of power with those charges. (DS9: "The Siege")
According to Gul Dukat later that year, education was power. (DS9: "The Maquis, Part I")
In 2371, Kira Nerys was worried about Kai Winn running the Bajoran Provisional Government and running unopposed in the elections for First Minister. She was afraid that Winn would never let go of power if it was given to her and claimed the only thing Winn cared about was her own power. (DS9: "Shakaar")
In 2373, Chakotay wondered how long the New Cooperative's ideals would last with the power to impose their collective will on others. (VOY: "Unity")
In 2375, Dukat claimed the Pah-wraiths would give Winn everything she ever dreamt of, including power and the adoration of her people. Winn later admitted to Kira that she had given in to the temptations of power. Kira told her to step down as kai as being in power is what led Winn down the wrong path. (DS9: "Strange Bedfellows")
In approximately 3074, a Kyrian arbiter claimed that Vaskans seized every opportunity to keep themselves in power. (VOY: "Living Witness")
In 3190, Federation President Laira Rillak transferred power to the Vice President in order to join a mission with the crew of the USS Discovery. It was Rillak's constitutional duty to inform Starfleet Commander-in-Chief/Fleet Admiral Charles Vance of this action. (DIS: "The Galactic Barrier")