Let That Be Your Last Battlefield
Frank "The Riddler" Gorshin, painted half black and half white, has pursued Lokai for the last 50,000 years. Eventually they end up on the Enterprise, when Kirk tells them to mellow the heck out until he's finished with the Enterprise's current mission to decontaminate a planet.
This isn't enough for Frank, who seizes control of the ship with his mind and starts steering it for his home planet. It takes a full five minutes for Kirk to think of telling someone to stun him. Of course, it doesn't work. After a tedious amount of messing about, Kirk decides to put the ship on auto-destruct (rather than, say, getting Scotty to rip out the dilithium crystals or something) and Frank eventually relents.
Later, they go find the home planet, which has been rendered long uninhabited, because Frank never once bothered to phone home and see how his family was doing. The moral, I guess, is don't neglect the ones you love in favour of your job.