<canvas width="600" height="400"></canvas>
<script>
var tela = document.querySelector('canvas');
var pincel = tela.getContext('2d');
// cabeça
pincel.fillStyle = 'darkgreen';
pincel.fillRect(200,50,350,300);
// olhos
pincel.fillStyle = 'black';
pincel.fillRect(250, 110, 90, 90);
pincel.fillRect(410, 110, 90, 90);
// nariz
pincel.fillRect(340, 200, 70, 100);
// boca ou barba
pincel.fillRect(300, 240, 40, 110);
pincel.fillRect(410, 240, 40, 110);
</script>