Thomas "Tom" Mason is a main character in the first, second, third, fourth and fifth season.
Tom is a former Boston University military-history professor, and becomes second-in-command of the 2nd Massachusetts Militia Regiment, a group of civilians and fighters fleeing Boston. In his wildest dreams, he would never imagine that his vast knowledge of warfare would be used in an actual war, much less a war against invaders from another planet. He has three sons Hal, Ben, and Matt, and his wife died early in the invasion. Tom befriends Anne Glass, eventually becoming romantically involved with her.
