Sinister
Six

Mysterio - from series 4 of the Animated line with a metallic green paintjob. Smoke base came from the Toybiz Spiderman Classics Mysterio.
Sandman - from the Spiderman 3 movie series by Hasbro. The old Sandman from the Toybiz Flip and Trap series was very well sculpted but a bit too big to be in scale. I really like all the interchangeable "sand hands" you could get from this figure (had to buy two different Sandman figures to get all of the hands though).
Vulture (background) - from the Hasbro Spiderman video game series. Nicely done, the old Toybiz Bug Busters series Vulture had a awesome sculpt but was too big to be in scale.
Doctor Octopus - Added in new tentacles, rubber band belt and removed his loincloth so he'd be shorter.
Electro - I really wanted him in his classic costume, this custom uses the head from the Electro in the Toybiz Spiderman Electro Spark line on a modified Giant Sized X-Men Banshee body. Still incomplete since he needs the lightning coming out of his gloves.
Kraven - Finally I am able to add an old-school comic-book styled Kraven to the lineup. This fantastic custom was made by customizer sporkythebold. I bought the figure from him on ebay. The old Toybiz Spider-Man Animated series Kraven was too short and the new Hasbro Spider-Man 3 Kraven was based off his video game appearance so I was especially happy he made this custom. Sporky really nailed all the details, from the hair to costume details. In the auction description he mentioned the base figure as a Toybiz Giant Sized X-Men Thunderbird.