Self-intersecting polygons, crossed polygons, or self-crossing polygons are polygons some of whose edges cross each other. They contrast with simple polygons, whose edges never cross.

Some types of self-intersecting polygons are:

• the crossed quadrilateral, with four edges
  • the antiparallelogram, a crossed quadrilateral with alternate edges of equal length
    • the crossed rectangle, an antiparallelogram whose edges are two opposite sides and the two diagonals of a rectangle, hence having two edges parallel
• Star polygons
  • pentagram, with five edges
  • hexagram, with six edges
  • heptagram, with seven edges
  • octagram, with eight edges
  • enneagram or nonagram, with nine edges
  • decagram, with ten edges
  • hendecagram, with eleven edges
  • dodecagram, with twelve edges
  • icositetragram, with twenty four edges
  • 257-gram, with two hundred and fifty seven edges