The General Motors LS-based small-block engines are a family of V8 and V6 engines designed and manufactured by American automotive company General Motors. First introduced in 1997, the family is a continuation of the earlier first- and second-generation Chevrolet small-block engine, of which over 100 million have been produced altogether, and is also considered to be one of the most popular V8 engines ever. Spanning three generations, a new, sixth generation is expected to enter production soon. Various small-block V8s were and still are available as crate engines.

The Chevrolet small-block engine is a series of gasoline-powered V8 automobile engines, produced by the Chevrolet division of General Motors between 1954 and 2003, using the same basic engine block. Referred to as a "small-block" for its size relative to the physically much larger Chevrolet big-block engines, the small-block family spanned from 262 cu in (4.3 L) to 400 cu in (6.6 L) in displacement. Engineer Ed Cole is credited with leading the design for this engine. The engine block and cylinder heads were cast at Saginaw Metal Casting Operations in Saginaw, Michigan.