1. ONC says that Dolly, a long-standing pet form of Dorothy, is now more commonly used for Dolores. It is also now being used as a given name in its own right.
2. Scottish pet name for a feminine form of Gaelic Domhnall ("world ruler") or the Anglicized variant Donald.
Feminine forms include Doileag, Dolag, Dolanna, Dolina, Dollag, Dona, Donalda, Donaldina, Donella, Donna, Donnag.
Feminine pet names include Dol, Doll, Dolly, Donna, etc.
It has a rare occurrence in the 1841 Census of Aberdeenshire.
A Scottish correspondent [MC2] reports cases where either Molly or Polly was used as a pet name for Mary, but was sometimes developed to Dolly, although this is very unusual.