|Occupation||New York City Medical Examiner|
|Other family||Twin - brother Edgar|
|Appearances||Sidney Perlmutter - List of Appearances|
|Portrayed by||Arye Gross|
He is shown to have more than a few quirks, such as eating his lunch on the autopsy tables - reasoning that the disinfectants used in the morgue are so powerful that the morgue is "the cleanest room in the city" - and always has a sarcastic remark.
His diagnostic skills, however, are on a par with Lanie's, and they seem to share a mutual respect, if not a lot of screens time. Perlmutter frequently makes Castle the butt of his jokes or snide comments.