This Black Widow costume features a velvet dress and veil, but doesn't include the black rose bouquet.
Here's a welcome alternative to pink foofy princess costumes: a girl's Bride of Darkness costume.
It's not gothic, and doesn't really look like a mummy, but I like the creepy looks of this Gothic Mummy costume. It would work well as a dead bride costume.
Are the skulls on this skull fairy costume too cutesey? I really like the wings and overall look of this outfit.
The wig is what really makes this Monster Bride costume work.