Lee: Charles Lee is a general who fought for the colonists and was given a command by George Washington, instead of Hamilton. His command is taken away at the Battle of Monmouth for his incompetent leadership. He blames Washington for the losses of the colonists, leading to Laurens challenging him to a duel where Lee is injured.

Seabury: Samuel Seabury is a bishop and loyalist who takes to the streets and vocally urges people to support the king and Great Britain. He is met with substantial backlash, and challenged by Hamilton to support his beliefs.

Eacker: George Eacker is a New York lawyer who makes a speech disparaging Alexander Hamilton. He agrees to a duel with Philip Hamilton over the same remarks. In the duel, which takes place at Weehawken, New Jersey, Eacker dishonorably shoots and kills Philip, who was aiming his pistol at the sky, a sign meant to show the shooter's intent to throw away their shot.

Doctor: Present at Phillip Hamilton's death. He explains to Alexander what has happened to his son.

Any other characters: n/a

(Source: https://www.gradesaver.com/hamilton/study-guide/character-list)