<Ul> <Li> Kate Callahan (Jennifer Love Hewitt), Former FBI undercover agent and supervisory special agent (season 10) </Li> </Ul> <Li> Kate Callahan (Jennifer Love Hewitt), Former FBI undercover agent and supervisory special agent (season 10) </Li> <Dl> <Dd> Callahan, as mentioned in the season 10 premiere, previously worked under Andi Swann's team, which is also Ashley Seaver's team since she left the BAU . She is a "seasoned undercover agent whose stellar work at the FBI has landed her a coveted position with the Behavioral Analysis Unit ." She and her husband, Chris, have been the guardians of Kate's teenage niece, Meg, since Meg was a baby following her parents' deaths in the September 11, 2001, attacks . Kate and Chris discover they are expecting a baby in the middle of season 10, coinciding with the actress's real - life pregnancy . At the end of season 10 she decides to take a year off and raise her baby . As of season 12, she has not returned, but producer Erica Messer has stated the door was open should Hewitt choose to return to the show . </Dd> </Dl> <Dd> Callahan, as mentioned in the season 10 premiere, previously worked under Andi Swann's team, which is also Ashley Seaver's team since she left the BAU . She is a "seasoned undercover agent whose stellar work at the FBI has landed her a coveted position with the Behavioral Analysis Unit ." She and her husband, Chris, have been the guardians of Kate's teenage niece, Meg, since Meg was a baby following her parents' deaths in the September 11, 2001, attacks . Kate and Chris discover they are expecting a baby in the middle of season 10, coinciding with the actress's real - life pregnancy . At the end of season 10 she decides to take a year off and raise her baby . As of season 12, she has not returned, but producer Erica Messer has stated the door was open should Hewitt choose to return to the show . </Dd>

Who has been in every episode of criminal minds