Here's a try...
1.
Colors: Red, Black, Green, Navy
Keyboard keys: Shift, Option, Control, Alternate
Fictional characters: (James) Bond, (John) Shaft, (Jack) Sparrow, (Lois) Lane
And that leaves 4....
Flap, Book, Stock and Fra... Which all share the characteristic of: not belonging to any of the other three groups.
Alternately, I think it's interesting that
FRA, Navy, Sparrow and Shaft can all be linked together... kinda sorta...
Haven't figued out how the rest sort themselves out if this really is a group though.