There was a little girl,
Who had a little curl,
Right in the middle of her forehead.
When she was good,
She was very good indeed,
But when she was bad she was horrid.

Henry Wadsworth Longfellow (1807-1882) American poet

“There Was a Little Girl,” st. 1 (c. 1850)
    (Source)

Often printed with "She was very, very good" for the penultimate line, and sometimes with "And when she was bad" (e.g.).

His son, Ernest, says that Longfellow composed the rhyme while walking back and forth with his infant second daughter (Alice Mary, b. 1850). There is some dispute about this, as well as his authorship of the other stanzas of the poem.