Animorphs is one of the iconic middle-grade series of the 90’s. The books are short and easy to read with simple plots about a group of teens fighting a secret alien invasion by turning into animals. The first several books are written by Katherine Applegate and then later by several ghost writers. The series was published under the name K. A. Applegate because it was believed boys wouldn’t read a book by a female author. (Because turning into animals and battling aliens clearly wouldn’t have been cool enough on its own. /sarcasm)

•  Animorphs (Main Series)
  1. The Invasion (Review)
  2. The Visitor (Review)
  3. The Encounter (Review)
  4. The Message (Review)
  5. The Predator (Review)
  6. The Capture (Review)
  7. The Stranger (Review)
  8. The Alien (Review)
  9. The Secret
  10. The Android
  11. The Forgotten
  12. The Reaction
  13. The Change
  14. The Unknown
  15. The Escape
  16. The Warning
  17. The Underground
  18. The Decision
  19. The Departure
  20. The Discovery
  21. The Threat
  22. The Solution
  23. The Pretender
  24. The Suspicion
  25. The Extreme
  26. The Attack
  27. The Exposed
  28. The Experiment
  29. The Sickness
  30. The Reunion
  31. The Conspiracy
  32. The Separation
  33. The Illusion
  34. The Prophecy
  35. The Proposal
  36. The Mutation
  37. The Weakness
  38. The Arrival
  39. The Hidden
  40. The Other
  41. The Familiar
  42. The Journey
  43. The Test
  44. The Unexpected
  45. The Revelation
  46. The Deception
  47. The Resistance
  48. The Return
  49. The Diversion
  50. The Ultimate
  51. The Absolute
  52. The Sacrifice
  53. The Answer
  54. The Beginning

Additionally there were several companion books that expanded and helped explain the universe. There was even a failed spin-off.

• Megamorphs
  • The Andalite’s Gift
  • In the Time of Dinosaurs
  • Elfangor’s Secret
  • Back to Before
• Chronicles
  • The Andalite Chronicles
  • The Hork-Bajir Chronicles
  • Visser
  • The Ellimist Chronicles
• Alternamorphs
  • The First Journey
  • The Next Passage