Celluloids are a class of materials produced by mixing nitrocellulose and camphor, often with added dyes and other agents. Once much more common for its use as photographic film before the advent of safer methods, celluloid's common present-day uses are for manufacturing table tennis balls, musical instruments, combs, office equipment, fountain pen bodies, and guitar picks.

Nitrocellulose-based plastics slightly predate celluloid. Collodion, invented in 1848 and used as a wound dressing and an emulsion for photographic plates, is dried to a celluloid like film.

The first celluloid as a bulk material for forming objects was made in 1855 in Birmingham, England, by Alexander Parkes, who was never able to see his invention reach full fruition, after his firm went bankrupt due to scale-up costs. Parkes patented his discovery as Parkesine in 1862 after realising a solid residue remained after evaporation of the solvent from photographic collodion.

Parkes patented it as a clothing waterproofer for woven fabrics in the same year. Later Parkes showcased Parkesine at the 1862 International Exhibition in London, where he was awarded a bronze medal for his efforts. The introduction of Parkesine is generally regarded as the birth of the plastics industry. Parkesine was made from cellulose treated with nitric acid and a solvent. The Parkesine company ceased trading in 1868. Pictures of Parkesine are held by the Plastics Historical Society of London. There is a plaque on the wall of the site of the Parkesine Works in Hackney, London.

In the 1860s, an American, John Wesley Hyatt, acquired Parkes's patent and began experimenting with cellulose nitrate with the intention of manufacturing billiard balls, which until that time were made from ivory. He used cloth, ivory dust, and shellac, and on April 6, 1869, patented a method of covering billiard balls with the addition of collodion. With assistance from Peter Kinnear and other investors, Hyatt formed the Albany Billiard Ball Company (1868–1986) in Albany, New York, to manufacture the product. In 1870, John and his brother Isaiah patented a process of making a "horn-like material" with the inclusion of cellulose nitrate and camphor. Alexander Parkes and Daniel Spill (see below) listed camphor during their earlier experiments, calling the resultant mix "xylonite", but it was the Hyatt brothers who recognized the value of camphor and its use as a plasticizer for cellulose nitrate. They used heat and pressure to simplify the manufacture of these compounds. Isaiah Hyatt dubbed the material "celluloid" in 1872. The Hyatts later moved their company, now called the Celluloid Manufacturing Company, to Newark, New Jersey.

Over the years, celluloid became the common use term used for this type of plastic. In 1878 Hyatt was able to patent a process for injection moulding thermoplastics, although it took another fifty years before it could be realized commercially, and in later years celluloid was used as the base for photographic film.

The development of celluloid was partially spurred by the desire to reduce reliance on ivory, with its shortages caused by overhunting. An 1883 invention allowed celluloid manufacturers to imitate the distinctive graining of ivory, and by the end of 19th century celluloid was marketed as a lighter (and three times cheaper) ivory substitute under the names "Ivarine", "Ivaleur", "French Ivory", "Parisian Ivory", "Grained Ivory", and "Ivory Pyralin".

English inventor Daniel Spill had worked with Parkes and formed the Xylonite Co. to take over Parkes' patents, describing the new plastic products as Xylonite. He took exception to the Hyatts' claims and pursued the brothers in a number of court cases between 1877 and 1884. Initially the judge found in Spill's favor, but ultimately it was judged that neither party held an exclusive claim and the true inventor of celluloid/xylonite was Alexander Parkes, due to his mention of camphor in his earlier experiments and patents. The judge ruled all manufacturing of celluloid could continue both in Spill's British Xylonite Company and Hyatt's' Celluloid Manufacturing Company.