C5

C5 is a designation used in multiple domains, including transportation, biology, packaging, and chemistry. The term does not refer to a single object but to several distinct entities sharing the same abbreviation.

Chevrolet Corvette C5, produced 1997–2004, is the fifth generation of the Corvette. It introduced a new body and chassis, a mid‑cycle engine update with the 5.7 L small-block V8 (LS1), and an independent rear suspension; it was available as coupe and convertible.

Lockheed C-5 Galaxy is a large strategic airlifter developed for the U.S. Air Force; first flown in 1968, entered service in 1969. It is one of the largest aircraft used for heavy lift missions, capable of carrying outsized cargo and military equipment across long distances. The aircraft was later updated to the C-5M Super Galaxy with upgraded engines and avionics.

Complement component 5 (C5) is a plasma protein in the complement system of the immune response; when cleaved by C5 convertase, it yields C5a and C5b. C5a is a potent inflammatory mediator; C5b initiates the assembly of the membrane attack complex, contributing to lysis of target cells. Therapeutic C5 inhibitors are used to treat certain blood disorders such as paroxysmal nocturnal hemoglobinuria and atypical hemolytic uremic syndrome.

In paper sizes, C5 is a standard envelope size, part of the ISO C-series, measuring 162 by 229 millimeters, designed to hold a single A4 sheet folded once.

In chemistry and biochemistry, "C5" commonly denotes a five-carbon unit or fragment, such as the five-carbon skeleton in pentane (C5H12) and related compounds.