Not exactly a "comeback" from retirement, but I'll vote for Dai Takahashi's successfull "comeback" from that leg surgery
I actually witnessed his "comeback " on Friends On Ice last week. He was just gorgeous! Skated his new EX to a quiet modern piano piece "Luv Letter" (by DJ Okawari). All his jumps were in great speed, height and sharp pivot, beautiful soft landing with flow. Foot work was as good as ever, with deep/ shallow edges. Most improved was his spins. He seemed to spare a lot of time practising his spins when he couldn't do his jumps yet. His physical training paid well too, he noted in a TV interview. The training granted him more flexibility and far more strech- the layback spin was stunning. Just beautiful.
I just can't wait to see his competition programs. With the brilliant package he has, I'm sure he will be on the podium even without a quad.
Sorry for the long comment... just had to spill my excitement out!
GO DAISUKE!