An evolution of the 1964 DOHC prototype “XJ13” engine, the Jaguar V12 engine is a family of SOHC internal combustion V12 engines with a common block design, that were mass-produced by Jaguar Cars for a quarter of a century, from 1971 to 1997, mostly as 5.3‑litres, but later also as 6‑litres, and 7‑litre versions that were deployed in racing. Except for a few low-volume exotic sports car makers, Jaguar's V12 engine was the world's first V12 engine in mass-production. For 17 years, Jaguar was the only company in the world consistently producing luxury four-door saloons with a V12 engine. The V12 powered all three series of the original Jaguar XJ luxury saloons, as well as its second generation XJ40 and X305 successors.

A V12 engine is a twelve-cylinder piston engine where two banks of six cylinders are arranged in a V configuration around a common crankshaft. V12 engines are more common than V10 engines. However, they are less common than V8 engines.