Mel

Longer feminine forms for Mel could be Melpomene, Philomel, Philomela, Florimel, Pamela, Melba, Meliora, Carmel, Carmella, Amelina, Camellia, Demelza, Eumelia, Ermelinda, Melesina, Melicent, Melita and Melva.

Mel can also be used as a short form of Melania, Melisa, or other related names.

In Portugal, until a few weeks ago, Mel wasn't allowed as girls' first name but now with the new laws that allow Mel for girls, I think the name's popularity will increase a lot in the next years. However, Mel was already popular as a nickname for Melissa, Melanie, Melania, Melina,...
It's a really cute name because it means "honey" in Portuguese.