From The Simpsons Library of Wisdom's The Homer Book.

As Homer's guardian angel, Colonel Klink appears to show Homer how miserable his life would be if had married Mindy Simmons instead of Marge.

Who he is: Fictional German P.O.W. camp colonel from '60s TV series "Hogan's Heroes."

Identifying marks: Groove in upper left cheek from monocle.

Homer's obsession: Loves to taunt Klink with knowledge of secret antics by Hogan and his men.

True identity: Sir Isaac Newton.

Reason for charade: To appear as someone Homer would recognize and revere.

[Caption of Homer at the bottom of the page saying "Colonel Klink! Why have you forsaken me?"]