Strange Matter is a children's action/adventure supernatural horror book series created by Marty M. Engle and Johnny Ray Barnes Jr. The series takes place in the fictional town of Fairfield. It centers on children attending Fairfield Middle School who encounter paranormal situations. Each book in the series features a new protagonist and a new situation. Some situations or characters are used more than once, but either way, it is a new situation. It series was published between 1995 and 1997.

Strange matter is a particular form of quark matter, usually thought of as a “liquid” of up, down and strange quarks. It is to be contrasted with nuclear matter, which is a liquid of neutrons and protons (which themselves are built out of up and down quarks), and with non-strange quark matter, which is a quark liquid containing only up and down quarks. At high enough density, strange matter is expected to be color superconducting. Strange matter is hypothesized to occur in the core of neutron stars, or, more speculatively, as isolated droplets that may vary in size from femtometers (strangelets) to kilometers (quark stars).

In particle physics, strangeness ("S") is a property of particles, expressed as a quantum number, for describing decay of particles in strong and electromagnetic reactions, which occur in a short period of time. The strangeness of a particle is defined as:

where n represents the number of strange quarks  and n represents the number of strange antiquarks .