This is what i have so far but i'm sure to be missing some.
Wielders:
"Old Man"
“Temnota”
Asylum I
Andras Bertesy
Black Mamba (Tanya Sealy)
Blackout (Marcus “Mark” Daniels)
Carnage (Cletus Kasady clone)
Cloak (Tyrone Johnson)
Cloak Imposter (Reginald Mantz)
Crown/Hunger
Dagger (Tandy Bowen) (briefly)
Dark Tower
Darkling/Asylum II (Henrique Manuel Gallante)
Darkstar I (Laynia Sergeievna Petrovna (Krylova))
Darkstar II (Sasha Roerich)
Darkstar III (Reena Stancioff)
Dead Ringer (Louis "Lou" Dexter)
Death Reaper
Deathurge
Doctor Dark (Kane Tucker)
Doorman (DeMarr Davis)
Dusk (Cassandra “Cassie” St. Commons)
Ecstasy (Renée Deladier)
Jack Chain
Left Hand (Diego Casseas)
Left Hand's daughter
Mister Negative
Moon Knight
Nightfall
Nightside I
Nightside II
Nightwind
Noir (Sa’ida Zebari)
Norio (surname unrevealed)
Opsidian
Quagmire (Jerome Myers)
Ratri (Randy Tate)
Shade (Nick Shank) - Marvel TSR Games character
Shade/Darkveil (Darnell Wade)
Shadowoman/Sepulcre (Jillian Marie Woods)
SHOC I
SHOC II (Todd Fields)
Shroud (Maximillian Quincy Coleridge)
Silhouette (Janelle Chord (legally changed form Silhouette Chord))
Smuggler (Conrad “Connie” Josten)
Spot (Dr. Johnathon Ohnn)
Vanisher
Vector (Grace Tam)
X'iv
Others / Possibles:
Asylum III
Blacklight
Dark
Dark-Crawler
Darkhawk I
Darkhawk II
Exile (Victor Kohl)
Gloom (Jordan Lewis)
la Nuit (Pierre Truffaut)
Mandarin
Mandarin (Temujin)
Malekith
Monotony Man
Oblivion
Shadowshift (Jamie Dansig)
Specter (Dallas Gibson)
Tentakill (Lars Anthony Hanson)
Umbra (Patrick Nesbitt)