Here is Pauley Perrette's favorite episode of NCIS. Like much of the cast, Perrette's Abigail "Abby" Sciuto was introduced during the show's backdoor pilot on legal drama JAG. 

The Naval Criminal Investigative Service led by Mark Harmon's Gibbs was introduced during JAG's eighth season, and they soon earned their own solo series. 

NCIS got off to a slow start but over time became one of the most popular procedurals on television. This is likely down to the show's likable cast of characters, including Ziva, McGee and Abby.

Pauley Perrette's Abby is famed for her gothic look, her many tattoos, love for a caffeine drink dubbed Caf-Pow, and her relentlessly cheerful demeanor.  

She served as a forensic scientist on the series and was a regular source of comic relief. Perrette credits NCIS creator Donald P. Bellisario for Abby's personality 

Prior to her exit following season 15 episode "Two Steps Back," Abby had appeared in almost every episode.  

Her exit from the series followed behind-the-scenes issues with co-star Harmon, who later left NCIS during season 19.  

Maybe the actor could be persuaded to make a cameo whenever NCIS finally comes to a close, but it's doubtful she would ever return to the series full time.