DOTA (defense of the ancients) is a very popular Warcraft III mod focused around heroes. There are troops and defence towers but you don't actually control them, you just control your hero. As your hero fights the hero gains experience and gold which can be used to upgrade your hero. It's best described as Real Time Tactics as opposed to Real Time Strategy as the base building has been completely removed.
The recently released Demigod is a good example of a professional game based around the idea. League of legends, is another game that is currently in the works with similar gameplay. Part of the time worked on the DOTA mod which is quite an interesting piece of news. With such similar games being released, it's inevitable that people will compare them. I'll be keeping a close eye on both to see which is more successful.