Feldman, who portrays guardian angel Fred on the Lifetime series, will play a new employee at Sterling Cooper Draper Pryce. He'll make his debut in this Sunday's episode, airing at 10/9c on AMC.
The news of Feldman's casting coming just days before his debut is just more proof at how much of a spoilerphobe series creator Matthew Weiner is.
Mad Men returned last week to 3.5 million viewers. While those aren't Walking Dead numbers — that season finale attracted 8 million total viewers — it's still a series high for the AMC period drama.