A 1000 sided shape is called a Chiliagon.
Here's a list! 1. Henagon or Monogon 2. Digon 3. Trigon or Triangle 4. Tetragon or Quadrilateral 5. Pentagon 6. Hexagon 7. Heptagon 8. Octagon 9. Nonagon or Enneagon 10. Decagon 11. Hendecagon 12. Dodecagon 13. Tridecagon 14. Tetradecagon 15. Pentadecagon 16. Hexadecagon 17. Heptadecagon 18. Octadecagon 19. Nonadecagon or Enneadecagon 20. Icosagon 21. Icosakaihenagon 22. Icosakaidigon 23. Icosakaitrigon 24. Icosakaitetragon 25. Icosakaipentagon 26. Icosakaihexagon 27. Icosakaiheptagon 28. Icosakaioctagon 29. Icosakainonagon or Icosakaienneagon 30. Triacontagon... 40. Tetracontagon... 50. Pentacontagon... 60. Hexacontagon... 70. Heptacontagon... 80. Octacontagon... 90. Nonacontagon or Enneacontagon... 100. Decacontagon or Hectagon... 1000. Chilliagon... 10000. Myriagon... Hope this helps!