Sir Robert Abbott Hadfield, 1st Baronet FRS (28 November 1858, Sheffield-30 September 1940, Surrey) was an English metallurgist, noted for his 1882 discovery of manganese steel, one of the first steel alloys. He also invented silicon steel, initially for mechanical properties (patents in 1886) which have made the alloy a material of choice for springs and some fine blades, though silicon steel has also become important in electrical applications for its magnetic behaviour.

Hadfield's father, also named Robert Hadfield, owned Hadfield's Steel Foundry in Sheffield and was one of the first manufacturers of steel castings. The younger Hadfield took over the business in 1888 and built the firm into one of the largest foundries in the world. He published over 200 papers on his metallurgical research. Hadfield was knighted in 1908 and made a baronet, of Sheffield in the East Riding of the County of York, in 1917. He was elected as a Fellow of the Royal Society in 1909, and a member of the Royal Swedish Academy of Sciences in 1912. He was awarded the John Fritz Medal in 1921 and the Albert Medal (RSA) in 1935, both for his contributions to metallurgy.

Robert John (born Robert John Pedrick, Jr., 1946, Brooklyn, New York) is an American singer-songwriter.

He is best remembered for the 1979 hit, "Sad Eyes". This song, which features John's falsetto vocals, reached Number One on the Billboard Hot 100. Earlier, in 1963 he recorded as the lead singer with Bobby & the Consoles. Recording for Diamond records, they had a small local hit with "My Jelly Bean".

John, then known as Bobby Pedrick, first hit the pop chart in 1958 when he was only 12 years old with "White Bucks and Saddle Shoes", written by Doc Pomus and Mort Shuman. By 1965 he had changed his name and signed with MGM records for two ill fated singles. In 1967 he signed a contract with Columbia records and released a string of singles with help from writing partner Mike Gately. After a short tenure with Herb Alpert's A&M records (1970–71), 1971 brought his next hit, a cover of The Tokens' 1961 hit "The Lion Sleeps Tonight" which climbed to #3 in 1972. This disc sold over one million copies, and received a gold disc awarded by the Recording Industry Association of America on March 15, 1972.

John Charles Heywood Hadfield, (June 16, 1907 - October 10, 1999) was a British author and publisher, best known for his novel Love on a Branch Line.

Born in Birmingham, he moved to Suffolk just prior to the closure of the Mid-Suffolk Light Railway branch line from Haughley to Laxfield and it was this that is said to have inspired the novel Love on a Branch Line .

After leaving school, Hadfield worked as an editor at the publishing firm of J. M. Dent in London. During World War II as Book Officer for the British Council he formed a unit translating books into Arabic. On returning to civilian life, he founded Cupid Press which specialised in limited edition anthologies of poetry . In 1957 he published 'A Book of Britain' an anthology of words and pictures covering five hunddred years of art, articles and poems celebrating the best of British culture.