I like Tabitha, I know two (adult and teenage) and so don't think of it as a cats name.
Also love Claudia - no particular dark meaning I don't think but similar feel.
Bathsheba - I went through a Hardy phase as a teen and really wanted to name a daughter this!
Seren - means little star I think. Serena is nice too.
Autumn is lovely, one of my faves, my favourite season too.
Aurelia - meaning 'golden', not dark but definitely Autumnal
Rhea - "a flowing stream" - again not dark exactly but earthy, bit pagan feeling
Pagan - maybe?
Octavia - (October the 8th month of Roman calendar)
Ramona - Google suggest this means 'protecting hands'
Opal - birthstone of October, beautiful stone
Blaize
Amoret - from Spenser's "The Faerie Queen"
Amabel
Sage - from the herb or meaning Prophet
Xanthe
Rain
Adrianne/ Adriana - again google suggests means 'dark one' , also Arianna which I love ever since I taught a gorgeous little girl of that name
Blake - name site suggest it means pale skinned but also 'dark'
Darcie/Darcy - "dark one" or dark haired
Eleena apparently means "the one who shines even during darkness"
Esmeray- "a dark moon"