The Buick V6, initially marketed as Fireball at its introduction in 1962, was a large V6 engine

V6 engine

A V6 engine is a V engine with six cylinders mounted on the crankcase in two banks of three cylinders, usually set at either a right angle or an acute angle to each other, with all six pistons driving a common crankshaft...

 used by General Motors. The block is made of cast iron and all use two-valve-per-cylinder iron heads, actuated by pushrods.

The 3800 was on the Ward's 10 Best Engines of the 20th century list, made Ward's yearly 10 Best list multiple times, and is one of the most-produced engines in history.