Adolf Carl Noé
Adolf Seilacher
Adolphe-Théodore Brongniart
Alberto Angela
Alberto Cobos
Alexander Kellner
Alexander V. Markov
Alexandr Rasnitsyn
Alexei Petrovich Pavlov
Alice Wilson
Allan Bé
Allison R. Palmer
Alois Humbert
Altangerel Perle
Amadeus William Grabau
Amanz Gressly
Amos Henry Worthen
André Cailleux
Andre Keyser
Andreas Kornhuber
Annalisa Berta
Anne Dambricourt-Malassé
Annie Montague Alexander
Anthony Fiorillo
Anthony Hallam
Anton Ramovš
Antonin Fritsch
Anusuya Chinsamy-Turan
Armand de Ricqlès
Arthur Smith Woodward
Atílio Munari
August Foerste
Auguste Bravard
Auguste Pomel