Who are the male characters in the novel, "The Great Gatsby", and what is their effect on the plot?

The central male characters are Nick Carroway, Jay Gatsby,
Tom Buchanan, and George Wilson.  Nick is the narrator of the story.  He tells the story
in retrospect, approximately two years after the fact. Nick is a good, reliable narrator
and we are told this in the opening lines of the novel when he says he is less inclined
than most people to judge others.  Nick's purpose is to tell us the story and let it
unfold in as accurate a fashion as possible.  He does, however, judge people, but it's
the judgement Fitzgerald wants the reader to have.  Jay Gatsby is the title character. 
Jay is the center of the story.  It begins with Gatsby as a mysterious name - a wealthy
man about whom little is known.  We gradually meet him and at first, we have to wade
through Gatsby's obvious lies about his past.  By the end of the story, Gatsby's past
and his mental state are exposed in such a way that we almost feel compelled to blush
and turn our heads away in polite embarrassment.  Gatsby is the love interest of Daisy
Buchanan who is married to another male lead, Tom Buchanan.  Gatsby and Tom are foils
and the two are finally pitted against one another face to face in a dramatic showdown
late in the story.  Tom is the opposite of Gatsby in many ways.  Tom was born rich and
lived a luxurious, spoiled life. Gatsby was born poor and worked his way to his wealth. 
Tom is mean and a bully, Gatsby is a nice man who is eager to please.  One thing they
have in common is they both want Daisy.  George Wilson is the last of the four male
leads.  He isn't in the story a great deal, but he plays an important part. He
represents the poor, down-trodden section of society in this novel that deals greatly
with class differences.  George is married to the woman, Myrtle, with whom Tom is having
an affair.  George thinks that Gatsby was driving the car that hit and killed Myrtle,
then sped away.  George, then, goes after Gatsby and kills him before committing
suicide.  Each male is in a slightly different socio-economic class in the book and that
is an important distinction as well.