"Long Tom was the physical weakling of the crowd, thin, not very tall, and with a none too healthy appearing skin. He was a wizard with electricity."

Long Tom Roberts  is 5'-4" tall and weighs 140 pounds. He has a chalky, white complection that somewhat resembles the color of a mushroom. His hair is also a light color. His front teeth are so large Monk calls them buck-teeth, one of which is gold.  Being called the "physical weakling" of Doc's crowd, is a deceptive statement. Many have made the mistake of looking at him and thinking him a push over. Despite his sickly appearance, he has never been known to be ill a day in his life. In fact, he can whip nine of ten men off the street. The tenth would wish he hadn't even started. When aroused he demonstrates such a fury that even the bullish Monk and Renny have been known to back off.
 
He received his nickname of "Long Tom" over an incident that occured during The Great War. In defense of a small european village he loaded an old seventeenth century long tom cannon with scrap metal and successfully held of a group of attacking German soldiers. He was in command of a group of Army reconnaissance scouts that utilized a newly developed communication radio system designed by Long Tom himself.

Long Tom's electrical genius is matched by only a few. He received his formal education in Electrical Engineering and was found to be so gifted that he was afforded the opportunity to take his post-graduate training as an apprentice to both Edison and Steinmetz. His electrical patents run into the hundreds. And he has become the weathiest of all of Doc's aids because of them. His lifestyle is miserly, though. He lives in a run-down building on Amsterdam Avenue in a small room off his basement laboratory.

For the most part, Long Tom is a mysogynist (a woman hater) although he has a secret crush on Pat Savage, but who doesn't. He falls in love for the first time with Lam Benbow, in The Feathered Octopus, but apparently not enough to get married.

Over the years, Long Tom has developed and maintained a multitude of electrical and electronic devices and weapons that Doc and his men have used in their arsenal against evil. This tends to keep Long Tom busy in his lab, or in Doc's lab at the penthouse much of the time. He also shares Renny's situation of being called on to oversee major electrical projects around the world.