Hexatiles can fill the plane along the boundaries of a triangular grid, with angles 60°. All hexatiles have their vertices and edges along the vertices and edges of triangular graph paper.
A polyiamond is a tile constructed by the union of edge-to-edge equilateral triangles, used in puzzles to fill open or closed domains in the plane.
Tilings of simple Hexatiles
Clear on any image to enlarge.