<meta charset="UTF-8">
<canvas width="600" height="400"></canvas>
<script>
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
//cabeça.
pincel.fillStyle = "darkgreen";
pincel.fillRect(0,0,400,400);
//olhos
pincel.fillStyle = "black";
pincel.fillRect(50,100,100,100);
pincel.fillRect(250,100,100,100);
//boca ou barba
pincel.fillRect(150,200,100,150);
pincel.fillRect(100,250,50,150);
pincel.fillRect(250,250,50,150);
</script>