Besides Mentioned Before...

If You in to the Pythons You can Consider Black Sumatran Short tail Python.. some of them Are Really really Dark...

There is Morph of Boa Called Black Boa.. Somebody was posting Pictures here not so long
Ago..

European Grass Snake (Natrix Natrix) in black with Yellow ears...

There Is couple Variations of Pretty Dark African House Snakes...

Is a lot of Choices.. Just Dig for them..