Clues:[contextual images] [Fanta logo on treble clef] [Winning slot machine]
Instructions: Name That Sith
_ _ I _ _ _ _ _
The 'Sith' in question is...
...not an adherent of the Dark Side in Star Wars (as you might expect), but actually Cait Sith, the character from the video game Final Fantasy VII.
Artwork by Tetsuya Nomura.
There are several clues in the images:
1. 'At last' in the title connects with Final, while the Fanta logo in the image is in the position of the 'C' note on the musical stave, giving us 'Fanta C', or Fantasy.
2. The crown in both the title and the image reflects the fact that the character wears a crown as part of his usual outfit (see the image above).
3. The slot machine represents both the fact that Cait Sith is first encountered in the Gold Saucer, an enormous amusement park and gambling spot, and the fact that one of his 'limit breaks' (i.e. special power-up moves) is called Slots, with a randomly selected outcome based on the spin of a slot machine.
4. The name satisfies the pattern provided - 8 letters, with third letter 'I'.
OP Edit:
Additionally, the jackpot on a slot machine is activated with 7-7-7, pointing to the game being Final Fantasy 7.