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
- the antiparallelogram, a crossed quadrilateral with alternate edges of equal length
- 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