<Li> Gerald McRaney as Dr. Nathan Katowski (aka "Dr. K"): The obstetrician who delivered Kate and Kevin . </Li> <Dl> <Dd> Dr. K was married to his wife, Caroline, for 53 years before she passed away in 1979 . He and Caroline had five children, the first of which was stillborn . Dr. K became a last - minute substitute for Rebecca's regular doctor, whose appendix burst . After one of the triplets is stillborn, he gave Jack some fatherly advice, and unknowingly convinced Jack to adopt Randall . Dr. K eventually dated and married Anne . They attended Jack's funeral, and Dr. K gave Rebecca some encouragement afterwards . </Dd> </Dl> <Dd> Dr. K was married to his wife, Caroline, for 53 years before she passed away in 1979 . He and Caroline had five children, the first of which was stillborn . Dr. K became a last - minute substitute for Rebecca's regular doctor, whose appendix burst . After one of the triplets is stillborn, he gave Jack some fatherly advice, and unknowingly convinced Jack to adopt Randall . Dr. K eventually dated and married Anne . They attended Jack's funeral, and Dr. K gave Rebecca some encouragement afterwards . </Dd> <Ul> <Li> Janet Montgomery as Olivia Maine: a theatre actress, Kevin's former stage partner and ex-girlfriend . </Li> </Ul>

Who plays rebecca boyfriend in this is us