Diminutives +‎ -y.

Ally (plural Allys)

A diminutive of the female given names Alice, Alison, Alexandra, or other names beginning with Al-[[]], from the Germanic languages or Ancient Greek.
- 1637–1638 (date written), Richard Brome, “The Damoiselle, or The New Ordinary. A Comedy.”, in A[lexander] Brome, editor, Five New Playes, […], London: […] Humphrey Moseley, Richard Marriot, and Thomas Dring, […], published 1653, →OCLC, Act I, scene i, signature A4, verso:
  Where’s my Girle? What Ally? Ally? / Enter Alice.
A diminutive of the male given names Alfred, Albert, Alan, Alexander, or other names beginning with Al-[[]], from the Germanic languages, the Celtic languages, or Ancient Greek.
Ally Love
- 1880, Alfred Tennyson, To Alfred Tennyson, My Grandson:
  Golden-hair'd Ally whose name is one with mine,
  Crazy with laughter and babble and earth's new wine

English