Eleanor “Ellie” Bishop leaves NCIS in the Season 18 finale as part of a secret undercover mission that requires her to publicly “disgrace” herself, while actress Emily Wickersham left the show simply because she was ready to move on after eight years in the role. On screen, Bishop admits to leaking old NSA files so she can be fired and disappear to work on a covert op with ex‑CIA instructor Odette Malone, telling Torres she will be gone “too long,” which closes her NCIS chapter but leaves the door open for a future return. Off screen, Wickersham praised the cast and crew in a farewell message and has stated in later interviews that there was no drama behind the scenes; she had simply reached a point in her career where she wanted new opportunities and a life beyond playing the same character for so many years.