Varnish has no SSL support; then what to use? As the developer of Varnish, Poul Henning, wrote back in 2011 on https://www.varnish-cache.org/docs/trunk/phk/ssl.html and again this year on https://www.varnish-cache.org/docs/trunk/phk/ssl_again.html Varnish has and will have no SSL support. 

If this is true for Apache servers (note  https://www.digitalocean.com/community/tutorials/how-to-configure-varnish-cache-4-0-with-ssl-termination-on-ubuntu-14-04 has instructions on how to configure both on Nginx), then I wonder what are Varnish alternatives for Drupal sites that need to be running through HTTPS (like, for example, Drupal Commerce sites)?
Content delivery platforms like CloudFlare and Fastly offer a wide range of SSL/TLS options. The question is, what are you trying to accomplish? Note that Varnish really won't do you any good for high transaction-volume sites because you're dealing with authenticated traffic. However, services like the ones listed above can be useful for delivering assets or for serving anonymous traffic.