Ra's al Ghul

Ra's al Ghul is the head of the League of Assassins, the father of Talia al Ghul and grandfather of Damian Wayne, and the former mentor of Bruce Wayne. His age is unknown, as he has used a Lazarus Pit for centuries to keep himself alive and healthy.
In the summer of 1991, when Bruce came to Nepal and spent time with the League of Assassins, Ra's was so impressed with him that he wanted him to become his successor as leader of the League. To Ra's, this would have additionally meant becoming the husband of his daughter who he knew would become an omega, even though she was unpresented at the time. Bruce left the League after he was told of these plans, disgusted with the prospect. Though many years have passed since then, the lessons Bruce learned from him have still had enough of an impact for him to recall them easily in the little man who wasn't there. Moreover, as revealed by Talia in the last chapter of that story, she and Ra's both still desire Bruce to become his successor and her husband, even with him being married to Tony Stark, although his continuing refusal has led them to come up with alternative plans.