Banquo

Spelt Ban + Quo. 

Banquo serves as a foil to Macbeth.

A foil being a character whose personality traits, actions or beliefs contrast with those of another character (in this case the contrast with Macbeth). This is used to highlight or emphasise the qualities of the main character. Macbeth bad - Banquo good.

Banquo is Thane of Lochaber of a commander of the Scottish army at the start, equal in rank to Macbeth.

Has a son Fleance.

To remember these facts use the following mnemonic:

Go to the bank to get a quote (Banquo) for a mortgage but being met by a banker who is wearing foil on his head.

Notice he has a lot of keys to lock bars (Lochaber) of gold away in the bank.