Banquo from The Tragedy of Macbeth

Why is this picture here again?
Because it's awesome, of course!

When we say "Macbeth" we probably think of Macbeth himself or his wife or the witches. We don't usually remember Banquo. Who is he anyway? He even dies in the third act.

However, his role is crucial in the play. His name is first mentioned in the play in scene two of act one, and together with the Macbeth's name:

DUNCAN
Dismay’d not this
Our captains, Macbeth and Banquo?

And this makes us understand, that they are compared throughout the play. This is confirmed in the scene of predictions. See how the witches hail Macbeth:

FIRST WITCH
All hail, Macbeth! hail to thee, thane of Glamis!
SECOND WITCH
All hail, Macbeth, hail to thee, thane of Cawdor!
THIRD WITCH
All hail, Macbeth, that shalt be king hereafter!

And Banquo:

FIRST WITCH
Lesser than Macbeth, and greater.
SECOND WITCH
Not so happy, yet much happier.
THIRD WITCH
Thou shalt get kings, though thou be none:
So all hail, Macbeth and Banquo!

And it is Banquo who first warns Macbeth to beware the predictions of witches:

And oftentimes, to win us to our harm,
The instruments of darkness tell us truths,
Win us with honest trifles, to betray’s
In deepest consequence.

When Macbeth becomes king, he starts to fear Banquo. I think, that apart from Banquo suspecting Macbeth of "playing foul", there is an issue of fertility/infertility between them. Banquo is promised to have his sons on the throne, and his name will continue in the generations, while Macbeth will perish, and all his treacherous deeds have been for nothing.

Banquo is not only the opposite of Macbeth, staying faithful and not seduced by the promises of future. His death takes place in the very middle of the play (scene three of act three) and marks the "point of no return" for Macbeth. There still was hope for the new king if he hasn't continued to kill, but he does. And after Banquo killing is easier and easier for Macbeth.

So Banquo, a nobleman of Scotland, is Macbeth's doppelgänger, a symbolical character that helps the reader get some important ideas of the play