The Sebright (IPA: /ˈsiːbraɪt/) is a British breed of bantam chicken. It is a true bantam – a miniature bird with no corresponding large version – and is one of the oldest recorded British bantam breeds. It is named after Sir John Saunders Sebright, who created it as an ornamental breed by selective breeding in the early nineteenth century.

The first poultry breed to have its own specialist club for enthusiasts, Sebrights were admitted to poultry exhibition standards not long after their establishment. Today, they are among the most popular of bantam breeds. Despite their popularity, Sebrights are often difficult to breed, and the inheritance of certain unique characteristics the breed carries has been studied scientifically. As a largely ornamental chicken, they lay tiny, white eggs and are not kept for meat production.

Sir John Saunders Sebright (1767–1846) was the 7th Sebright Baronet, and a Member of Parliament for Hertfordshire. In addition to breeding chickens, cattle and other animals, Sir John wrote several influential pamphlets on animal keeping and breeding: The Art of Improving the Breeds of Domestic Animals (1809), Observations upon Hawking (1826), and Observations upon the Instinct of Animals (1836).

Charles Darwin read Sir John's 1809 pamphlet, and was impressed with a passage that elaborated on how "the weak and the unhealthy do not live to propagate their infirmities". These writings, along with Darwin's correspondence via their mutual friend William Yarrell, aided Darwin in the inception of Darwin's theory of natural selection. Darwin's seminal work On the Origin of Species, first published in 1859, cited Sir John's experiments in pigeon breeding, and recalled "That most skilful breeder, Sir John Sebright, used to say, with respect to pigeons, that 'he would produce any given feather in three years, but it would take him six years to obtain head and beak.'" Darwin also cited Sir John extensively regarding the Sebright bantam, as well as pigeon and dog breeding, in his 1868 work Variation of Plants and Animals Under Domestication, his 1871 The Descent of Man, and Selection in Relation to Sex, and his book on Natural Selection (which was not published in his lifetime).

Sebright set out to create a very small bantam chicken with laced plumage similar that of the laced Polish. Although the exact makeup of the breed is uncertain, it is thought that he created the gold Sebright by cross-breeding a buff Nankin bantam hen, a small gold-spangled Hamburgh-like hen and a small hen-feathered Pit Game cock; he later created the silver Sebright by crossing his golds with a white Rosecomb cock bought from the new Zoological Gardens of the Zoological Society of London, established in 1826. It is also possible that the hen-feathering characteristic derived from the Belgian Campine breed rather than from Pit Game. In about 1810, Sebright founded The Sebright Bantam Club, which was the first single-breed association for chickens. In 1853 the Sebright was described in the Poultry Book of William Wingfield and George William Johnson, with an illustration by Harrison Weir. It was included in the original Standard of Excellence in Exhibition Poultry of William Bernhard Tegetmeier in 1865, and in the first Standard of Perfection of the American Poultry Association in 1874. Today, the breed is one of the ten most popular bantam chickens, according to the American Bantam Association.

In accordance with the intentions of their creator, the Sebright is an ornamental bantam, and is commonly seen in competitive poultry shows. As a true bantam, all Sebrights are very small in stature; males weigh an average of 22 ounces (620 grams) and females 20 oz (570 g). Their short backs, proportionally large breasts, and downward-pointing wings combine to create an angular, jaunty look.