Leonidas of Epirus
Leonidas of Epirus (Greek: Λεωνίδας ο Ηπειρώτης) or Leuconides (Greek: Λευκονίδης), was an Illyrian tutor of Alexander the Great. A kinsman of Alexander's mother, Olympias, he was entrusted with the main superintendence of Alexander's education in his earlier years, apparently before he became a student of Aristotle.
Leonidas of Epirus (Greek: Λεωνίδας ο Ηπειρώτης) or Leuconides (Greek: Λευκονίδης), was an Illyrian tutor of Alexander the Great. A kinsman of Alexander's mother, Olympias, he was entrusted with the main superintendence of Alexander's education in his earlier years, apparently before he became a student of Aristotle.

Teacher
Leonidas was a person of austere character, and trained the young prince in laconic discipline. He  was said to examine the chests which contained his pupil's bedding and clothes, to see whether Olympias had placed anything there that might minister to luxury. There were two excellent cooks (said Alexander afterwards) with which Leonidas had furnished him,—a night's march to season his breakfast, and a scanty breakfast to season his dinner.

Advice
On one occasion, when Alexander attended a sacrifice, he threw large quantities of incense on the fire, Leonidas admonished him to "be more sparing of it till you have conquered the country where it grows." Alexander sent him afterwards from Asia 600 talents' weight of incense and myrrh, "that he might no longer be penurious" (so ran the message) "in his offerings to the gods."  It may be questioned whether the rough discipline of Leonidas was not carried further than was altogether beneficial to Alexander's character.

References
Who's who in the age of Alexander the Great: prosopography of Alexander's empire  ISBN 978-1-4051-1210-9
Fox, Robin Lane. (1973) Alexander The Great This article incorporates text from a publication now in the public domain: Smith, William, ed. (1870). Dictionary of Greek and Roman Biography and Mythology. {{cite encyclopedia}}: Missing or empty |title= (help)