<canvas width = "500" height = "500"></canvas>
<script>
var pantalla = document.querySelector("canvas");
var pincel = pantalla.getContext("2d")
pincel.fillStyle = "grey";
pincel.fillRect(0,0,500,500);
function crear_Cubo(x, y, w, h){
pincel.fillStyle = "black";
pincel.fillRect(x, y, w, h);// posicion X Y
pincel.fillRect(500-(w+x), y, w, h);
}
//cabeza
pincel.fillStyle = "green";
pincel.fillRect(75,100,350,300); //w: ancho, h: alto
//ojos
crear_Cubo(125,170,90,90);
//crear_Cubo(210,70,90,90);
//nariz
crear_Cubo(215,260,70,100);
//boca
crear_Cubo(175,300,40,100);
</script>