There are only so many hours in the day, and if you're an evil villain, there's too much dirty work to do.
Often they are the funniest part of the story, and certainly have more personality than the evil overlord they work for. Revisit some of your favorites in this expandable list from Geekosystem. Link
So you get a henchman. But you can't just let him out there all alone. It's a big dark scary world, and he barely even has a name, much less any characterization! He needs a buddy.
Bonus points if the buddy is the physical opposite of the other, skinny where he is fat, or short where he is tall. Extra bonus points if you can use them as stand-ins to personify a much larger fighting force.
Often they are the funniest part of the story, and certainly have more personality than the evil overlord they work for. Revisit some of your favorites in this expandable list from Geekosystem. Link
They are not self employed, Team Rocket is a large and often competent criminal enterprise. They often refer to 'The Boss' and most of what they do is to gain esteem in his eyes. They also have their own bad-guy nemesis team in Butch and Cassidy, a far more functional duo of Team Rocket members.
Go Team Rocket!
*Henchmen 24, never forget!
http://en.wikipedia.org/wiki/List_of_James_Bond_henchmen_in_Diamonds_Are_Forever#Mr._Wint_and_Mr._Kidd
By Toscana