One of the completed pictures of my recent "Rarity is a Cyborg" Request Stream.
This is Rarity as The Borg Queen from Star Trek: First Contact
I had a very bizarre satisfaction when adding veins, making Rarity's skin ragged and malnourished, destroyed by the lack of blood running through her non-existent veins, and basically turning her into an (almost) soulless creature with an engine for a heart. But, you know, she's still her! That mane of hers looks as fabulous as always, because I have this idea that if Rarity ever got abducted by the Borg she'll do her best to keep her hair as primed as ever.
Also, two things relating MLP and The Borg. One, I always saw Queen Chrysalis as the Friendship is Magic equivalent to The Borg Queen; and two, I like to think that, when Rarity turned into Nightmare Rarity in the second MLP Comic Arc, they were inspired by the time when Piccard was abducted and assimilated by The Borg.
Art by James Corck