Here is a list of the main characters (and a short summary) in Mark Twain's The Adventures of Huckleberry Finn.

AUNT POLLY.  Tom's guardian.
AUNT SALLY.  Tom's aunt.
BOGGS.  A drunk from Bricksville.
WIDOW DOUGLAS.  Huck's adopted mother.
THE DUKE.  A con man who claims to be of royal birth.
HUCK FINN.  The main character is an independent spirit whose mother is dead and whose father is a drunken ne'er-do-well. His journeys along the Mississippi River is the basis of the story.
PAP FINN.  Huck's drunk of a father kidnaps his own son and beats him before Huck escapes.
BUCK GRANGERFORD.  The youngest boy of the Grangerford family, Buck is killed during the feud with the Shepherdsons.
EMMELINE GRANGERFORD.  She died young, leaving behind a number of poems and drawings that intrigue Huck.
JIM.  Miss Watson's runaway slave who joins Huck on his travels.
THE KING.  The Duke's partner in crime and grifting, he is eventually tarred and feathered.
JUDITH LOFTUS.  Huck meets her while dressed as a girl, but he doesn't fool her.
REVEREND SILAS PHELPS.  Tom's uncle.
TOM SAWYER.  Huck's sidekick and partner in crime. Tom joins Huck for part of his journey.
COLONEL SHERBURN.  A Southern gentleman who kills Boggs in Bricksville.
JUDGE THATCHER.  The father of Becky, he takes care of Huck's money for him and has Huck's best interests at heart.
MISS WATSON.  Sister of the Widow Douglas and Tom's owner.
THE WILKS SISTERS.  The girls who become orphans when their guardian dies. The King and Duke pretend to be their uncles. free in her will.