|Portrayed by||Blake Bashoff|
|First appearance||Public Relations|
Mark Kearney is Peggy's boyfriend.
When Peggy needs bail and hush money for a publicity stunt gone wrong, Mark accompanied her to Don's apartment. Don asked her if she wanted people to think that Sterling Cooper Draper Pryce was full of idiots, at which Mark jumped in. Don, slightly stunned asked who he was, to which Mark said that he was her fiancé. Later, Peggy questions why he would say that. Mark says that it just came out. ("Public Relations")
Later, Mark causes Peggy stress by trying to pressure her into having sex before marriage. Mark ironically accused Peggy of having traditional values and being "old-fashioned." While Freddy suggested to avoid sex before marriage if she wanted Mark to ever respect her but also suggested that refusing to sleep with him is, for the man, "physically uncomfortable." Eventually Peggy sleeps with Mark. ("Christmas Comes But Once a Year")
Peggy had to delay her plans with Mark, who was throwing a surprise party with her entire family. She told him it would be roughly 15 minutes before she could get there, but after an hour, she was still a no-show. After that point Mark asked if he should cancel. Peggy thought about leaving, but called the restaurant one more time, telling her that she would not make it. Peggy's mother, Katherine tells Peggy over the phone that Mark is "crestfallen" and that she is disappointed with her. He wondered why he would bother being nice to her and broke up over the phone. ("The Suitcase")