Frank J. Wilstach, comp. A Dictionary of Similes. 1916.

Ugly

Ugly as a scarecrow.
—Anonymous

Ugly as sin.
—Anonymous

As ugly as were ever born of mud.
—Thomas Carlyle

Ugly as the devil.
—Henry Fielding

Ugly as the devil’s dam.
—Richard Flecknoe

Ugly as a bear.
—William Shakespeare

Ugly as apes.
—Paulus Syllogus

Ugly as a worn-out cabhorse.
—Anton Chekhov

Ugly as the angel of a sign-board.
—Thomas Wade