C-3PO is a Premium Box Tsum. He is a Limited Time Event Tsum and is not obtainable through purchasing Premium Boxes outside of the event.
C-3PO will clear a horizontal line of Tsums. He is also considered a "Call a Friend" Tsum as he calls R2-D2 for his skill.
Skill Level Edit
Disney Tsum Tsum - C-3PO (Star Wars Puzzles Event)
Disney Tsum Tsum - C 3PO (Star Wars Puzzles Event) 2
C-3PO's skill clearing tsum tsums horizontally
Tsum tsums going to be cleared after C-3PO used his skill
Tsum tsums being cleared after C-3PO's skill is activated