TV Guide reports that she will play Tracy Keller, the ex-partner of G. Callen (Chris O'Donnell) in an upcoming episode. The pair will apparently share a complicated romantic past.
Nichols previously appeared alongside O'Donnell in the 1992 film Scent of a Woman. She also starred in the sixth season of 24 and currently features in supernatural ABC drama The Gates.
The actress confirmed that the character could return, noting that the role is "booked as guest star/recurring".
NCIS: Los Angeles returns to CBS on September 21.