There are seven main characters in the world of Chrono Trigger:

Crono The main hero
Marle Princess of Guardia
Lucca The Inventor Friend
Frog The Heroic Knight
Robo The Cool Robot
Ayla Prehistoric War Machine
Magus The man himself...

Plus a cast of many other Non Player Characters...

65,000,000 B.C.

  1. Kino - friend of Ayla, later leader of Ioka village. Kino does not like
     you at first.
  2. Azala - leader of the Reptiles, and is highly intelligent
  3. Old Man - leader of the Laruba village, lets you have access to the
     dactyl

12,000 B.C.

  1. Queen Zeal - the ruler of the Kingdom of Zeal
  2. Janus - son of Queen Zeal, heir to the throne
  3. Schala - daughter of Queen Zeal, also heir to the throne
  4. Doreen - sister of Masa and Mune
  5. Masa - an odd creature that helps you on your quest, part of the
     Masamune
  6. Mune - an odd creature that helps you on your quest, part of the
     Masamune
  7. Guru of Life - a.k.a. Melchior. He repairs the Masamune for you, and
     creates weapons
  8. Guru of Time - a.k.a. Gaspar. He created the Chrono Trigger
  9. Guru of Reason - a.k.a. Belthasar. Designed the Blackbird, Ocean
     Palace, and the Epoch
 10. Prophet - a.k.a. Magus. He has come from the future to defeat Lavos
 11. Dalton - the Queen's aide, and a pain in the butt
 12. Old Man - the leader of the earthbound ones

600 A.D.

  1. King Guardia the 21st - King of Guardia, 600 A.D.
  2. Queen Leene - Queen of Guardia, 600 A.D.
  3. Sir Cyrus - a noble knight who was defeated by Magus' army
  4. Yakra - a beast that kidnaped the Chancellor and took his place
  5. Chancellor - the person who has a tendency to be kidnaped, also creates
     a criminal justice system in the future
  6. Chef - the brother of the Knight Captain. They are feuding
  7. Knight Captain - a brave soldier, but feuds with his brother, the Chef
  8. Tata - a kid pretending to be the legendary hero
  9. Toma - a treasure hunter in search of the Rainbow Shell and Sun Stone
 10. Yakra XIII - trying to frame King Guardia to get revenge on your from
     400 years ago
 11. Fiona - a woman trying to save a forest
 12. Marco - husband of Fiona

1000 A.D.

  1. Taban - Lucca's Father
  2. Lara - Lucca's Mother
  3. King Guardia XXXIII - King of Guardia, father of Princess Nadia
  4. Queen Aliza - Queen of Guardia, passed away many years ago
  5. Chancellor - the prosecuting attorney, and another person after you
  6. Pierre - the defense lawyer
  7. Judge - the judge of your trial, also judge of King Guardia's trial
  8. Little girl - will vouch for you if you find her kitty
  9. Man - will testify against you if you steal his lunch
 10. Gato - big singing robot
 11. Jury Members - will determine your innocence or guilt
 12. Melchior - a sword smith who helps you on your quest, is a Guru from
     12,000 B.C.
 13. Ozzie VIII - leader of Medina Village, descendant of Ozzie from 600
     A.D.
 14. Bandeau - guy who wants to build a ferry route between Medina and Truce
 15. Fritz - son of weapon shop owner, put into jail

2300 A.D.

  1. Doan - descendant of the Director of the Info Center
  2. Johnny - the robot that turns into a trike who will race you across the
     ruins of Lab 32
  3. Belthasar - the Guru from 12,000 B.C. who has gone mad
  4. Nu - contains the memories of Belthasar
  5. Atropos - Robo's "girlfriend". Her memory has been corrupted by the
     Mother Brain
  6. Mother Brain - the computer in charge of the R series factory. It wants
     to destroy all humans

The End of Time:

  1. Old Man (Gaspar) - one of the Gurus from 12,000 B.C.
  2. Spekkio - The God of War. Spekkio will teach you magic, and give you
     items if you defeat him