If there's something Doctor Who is known for besides time travel hijinks, sonic screwdrivers, and regeneration, it's having a massive catalog of memorable monsters. With a new season of Doctor Who upon us, we're taking a look back at the Doctor's rogues gallery to highlight the most vicious monsters our favorite Time Lord has encountered.

Before we dive in, a couple of notes: We've excluded villains that don't fit the traditional definition of "monsters," so you won't find the Master on this list. Additionally, while some of these creatures originated in the classic series, each entry has appeared at least once on television since the 2005 revival. We believe the "modern" monsters are more impactful and align better with our focus. With that clarified, let's explore. Here are our top 20 Doctor Who monsters.

The Best Doctor Who Monsters of the Modern Era

21 Images