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

Thin

Thin as a groat.
—Anonymous

Thin as a rail.
—Anonymous

Thin as a snake.
—Anonymous

Thin as a wafer.
—Anonymous

Thin as famished rats.
—Anonymous

Thin as gold leaf.
—Anonymous

Thin as wall paper.
—Anonymous

Thin as a reed.
—Anonymous

Thin as a spindle.
—Anonymous

Thin as a toothpick.
—Anonymous

Thin as the shadow of a hair.
—Anonymous

Thin as a pair of shears.
—Arabian Nights

His poor body is as thin as a nail.
—Honoré de Balzac

Thin as the petal of the cotton blossom.
—Henry A. Clapp

Thin as a lath.
—Foundling Hospital for Wit, 1743

So thin that he was obliged to put lead in his shoes so as to not be blown away by the wind.
—Victor Hugo

Thin as a Ritz-Carlton sandwich.
—Stephen Leacock

Thin as a carriage painter’s arm.
—Abe Martin

Thin as a weasel.
—George Meredith

Thin as mist.
—George Meredith

Thin as the shell of a sound.
—George Meredith

Thin as a brief forgotten dream.
—Richard Monckton Milnes

A Spectre, thin as that dismal flame
That burns and beams, a moving lamp,
Where the dreary fogs of night encamp.
—T. Buchanan Read

Her body thin and bare as any bone.
—Thomas Sackville

Thin as a skeleton.
—Thomas Shadwell

Thin of substance as the air.
—William Shakespeare

Thin as Fraud.
—Percy Bysshe Shelley

Thinned, as the shades in a vision of spirits that sinned.
—Algernon Charles Swinburne

Thin as a costume worn by a Salome dancer.
—Walter Trumbull