The 19 best sci-fi TV shows of all time, according to critics

Science fiction has been around for a long time, and has been around since the earliest days of television with "The Twilight Zone" and the original "Star Trek" series. And it's not going away. In fact, it's only getting more popular.

With network shows like "The X-Files," "Lost," and Netflix's "Stranger Things" tackling the genre over the past few decades, sci-fi shows are reaching a broader audience than ever before. "Orphan Black" has found critical acclaim and premieres its final season June 10.

If you're new to sci-fi or a die-hard fan looking for more, here are the best sci-fi shows according to critics, based on scores from $4, which aggregates reviews of TV shows:

Note: superhero shows based on comic books were left out, along with older shows that don't have Metacritic scores ("The Twlight Zone," the original "Star Trek," the original "Doctor Who").