Ra's al Ghul

Using the Lazarus Pit to extend his life, Ra's mastered many forms of combat and tactics, especially swordplay. He built a massive international criminal organization with himself as its head. One arm was the League of Assassins. All members were fanatically loyal to their master. He took another wife and had a daughter, Talia, but his wife was killed by an embittered associate. The more Ra's lived and saw humanity overrun the world, destroying its natural resources, the more he despised people. As the industrial age got underway, Ra's began to focus more and more on ecological terrorism, hatching schemes to eliminate most or all human life on Earth while leaving nature untouched. Until he could find a way to do so, he manipulated world events from behind the scenes.

Over the centuries, Ra's had made a point of searching out and acquiring any Lazarus Pits in the world. When an island on which one was located was bought by Bruce Wayne, Ra's set out to destroy Wayne and acquire his business empire. While studying his quarry, Ra's discovered that Wayne was also Batman. Dr. Darrk, field leader of the League of Assassins, attempted a coup against Ra's by kidnapping his daughter Talia, but she was rescued by Batman, and she killed Darrk in self-defense. Soon after, Ra's approached Batman, asking for his help rescuing Talia, who had been abducted similarly to how Robin had just been taken. Batman later realized it was all set up by Ra's, who admitted it was a test to determine Batman's worthiness as his heir, since Talia was in love with him, and he'd passed.

Eventually, Batman learned the extent of Ra's empire and tried to bring him to justice. Ra's challenged him to a duel to the death. They fought for hours until Batman was stung by a scorpion. Ra's left him to die, but Talia gave him the antidote, and Batman finally captured Ra's. Imprisoned, Ra's got revenge by framing Batman for both his and Talia's murders. He'd faked their deaths, his goal being to make Batman a fugitive and force him to become his son-in-law, but the plan failed. However, Talia's feelings for Batman were reciprocated. Batman persuaded her to leave her father and join him, infuriating Ra's. The three made a truce to take down a terrorist, and while doing so, it was discovered Talia was pregnant. But following an apparent miscarriage, she chose to stay with Ra's.

Ra's unleashed a virus called The Clench on Gotham, and the city was quarantined. He almost realized his goal of wiping out humanity before Batman found a cure. Ra's briefly considered Bane as an alternate heir, but Talia was unimpressed with him. Later, another daughter of Ra's, Nyssa Raatko (a.k.a. Nyssa al Ghul), whom Ra's had abandoned, returned to seek vengeance on her father and sister. Ra's orchestrated a situation where he allowed Nyssa to mortally injure him, but his two daughters made peace between them and agreed to rule his empire together. Ra's died and, to ensure he could not return, was cremated. However, Ra's had taken steps to ensure his consciousness survived, and he could return in a suitable host body: that of his grandson, Talia's son with Batman, Damian (her fake miscarriage).

Damian's existence had previously been revealed to Batman by Talia and had been trained as the next Robin. Talia and Batman clashed over Damian's upbringing, but when Talia learned her father planned to kill her son in order to resurrect himself, she helped Batman fight Ra's. Batman offered his own body as a substitute host to spare his son, but Ra's wanted a younger one. Ultimately, a previously unrevealed son of Ra's going by the name the White Ghost offered himself instead. Ra's accepted, leading to his full resurrection. Since then, he has come to take pride in his grandson, viewing Damian as another potential worthy heir.