Gene Rainey was one of the main antagonists of the Angel episode "Happy Anniversary" - although in reality he was more of a pawn than a true villain. He was willing to risk universal paradox via freezing time so that he would not lose his girlfriend after he heard that she was planning on breaking up with him: thanks to the manipulation of the Lubber Demons his mad science almost destroyed the world itself.
Gene Rainey was a genius physicist studying Time Paradox and had found a way to effectively freeze time, however he was also emotionally insecure as he became depressed upon overhearing his girlfriend informing one of her friends that she planned on breaking up with him.
Unable to cope with his potential loss Gene attempted to freeze time so that he and his girlfriend would be frozen in the act of making love, in effect making a symbolic statement of eternal love, however while he was content with merely freezing himself and his lover a cult of Lubber Demons interfered with his work, making it so his experiment would start to freeze all of time on earth.
Gene was unaware that the Lubber Demons were doing this and also had no idea that he was considered a demonic messiah by these creatures as the one who would destroy humanity (which, arguably, he was.. since his actions could of destroyed everything).
Although Gene succeeds in freezing himself and his lover in time the process is undone by Angel to stop it spreading further and after the machine is destroyed Gene admits that he hadn't thought about his actions and that he had just wanted his lover back..
The ultimate fate of Gene is unknown but he is presumably still alive, though whether he managed to rekindle his relationship or find another is likely never going to be answered.