He is the head of a highly wealthy, upper-class family in Miami.
It is stated by Thomas Matthews that Ed Hamilton is a friend of the Miami Metro Police Department and that he has, in the past, made generous donations to the department. Following the death of Norma Rivera (the former maid of the Hamilton family), Hamilton admitted that he was having an affair with Norma and that they had sex shortly before she was murdered. Ed is also the father of Zach Hamilton, with whom it seems he has a distant relationship.
After Norma died, Hamilton began an affair with another employee, Sofia Fuentes, the next part of a series of affairs that resulted in his wife succumbing to alcoholism. Around this time, he sent his son to start seeing Dr. Evelyn Vogel, as Zach seemed to have a propensity for violence. Meanwhile, it's revealed that Zach was trying to save his mother from alcohol by stopping his father's affairs, which he attempted to do by killing Norma. When that failed, he tried to kill his own father, but Hamilton was saved by the intervention of Dexter Morgan, and Hamilton was oblivious to his son's attempt to kill him.