Dzou Yen - An admired Alchemist in the 4th Century B.C. in China, lived during the Zhou Dynasty in the state of Qi.  Capable of transmuting base metals into noble metals.
Lu Hsiang - Was sought out by the Emperor of China in 130 B.C. to transmute lead into gold.  Did a ritual that consisted of prayer, along with hours and hours of meditation to contact the Goddess Stove who reigned over medicine and cooking.  Was sentenced to death after having failed to transmute lead into gold for the Emperor.
Nicolas Flamel - Born in Paris, France in 1327.  Attended Beauxbatons Academy in the early 1300's.  He is the only known maker of the Philosopher's Stone.  Created the Elixir of Life along side his wife.  Wasn't only an Alchemist, but a Philosopher as well.  Helped create the essential rules and ethics for future Alchemists.  Gave copious amounts of money to Beauxbatons Academy.  Was assisted by Dumbledore on some of his works.
Professor Autumn Maddox - Direct descendant of Nicholas Flamel.  Attended Beauxbatons Academy.  Moved to the UK in 2000, and attended Hogwarts.  Graduated in 2006.
Phillipus Aureolus Theophrastus Bombastus von Hohenheim or Paracelsus - Born 160 years after Nicolas Flamel in 1493.  Lived during the Renaissance era.  Was a fiercely intelligent man.  Also a Physician by trade.  Named the element known as Zinc.  Created a chart known as the Harmony of Elements and Organs.

Zosimos of Panopolis - Born in 4th Century AD in Panopolis, Egypt.  Defined the term of Alchemy as "the composition of waters, movement, growth, embodying and disembodying, drawing the spirits from the bodies and bonding the spirits within bodies."  Attributed to the oldest known books in Alchemy which were translated into multiple languages.  First translated into Arabic.  "The ancient and divine writings say that the angels became enamoured of women; and descending, taught them all the works of nature. From them, therefore, is the first tradition, chema, concerning these arts; for they called this book chema and hence the science of chemistry takes its name.."  Had many dreams about the god Ion.  Though not much is known about his death, his life is passed down through Alchemists.
Kanada - Indian Alchemist.  Born around 6th Century B.C. near Gujarat, India.  Contributed to a branch of Alchemy called Rasavadam.  Theorized about the Four Aspects, but established the element Æther - matter that fills our universe above the sublunary sphere.  Not a widely popular idea.  Also contributed the first idea of the atom.  Believed an atom to be an indestructible particle of matter.  Also believed an atom to be eternal.  Believed it could be combined to achieve a certain outcome.  Theorized that you could combine atoms to produce biatomic molecules as well as triatomic molecules.