I sent a Walking Dead trading card to Andrew Lincoln back on 7/11/15. I got the card back unsigned on 2/8/18; 944 days later, but he included a 5 x 7 signed photo. This is my longest ttm return to date.
It's a black and white photo and it was signed with a silver paint pen, so the signature is a little hard to see on the scan.
Here is a close up of the signature.