The Arrowverse has grown from a relatively grounded comic book reality to a universe filled with aliens, metahumans, mystical beings, and of course Beebo. The universe's growth worked due to its gradual and sometimes seamless integration of otherworldly elements into its ongoing narrative.
This expansion has also extended to its villains, as the side of evil grows to match the side of the angels. The verse's villains range from everyday crime lords to metahumans and even cosmic entities whose scope is beyond what was faced in its early days.
Some baddies fare better than most, with the likes of Deathstroke and Reverse-Flash entering the upper echelon of comic book TV villainy, and characters such as Vandal Savage quickly faded into obscurity. It is also telling that some of these villains define the quality of their respective seasons, as seen with the excellent Prometheus being the primary protagonist of Arrow's excellent fifth season.
However, some villains have strong features across the Arrowverse but do not receive the accolades as some of their more well-known counterparts. Despite their relative lack of notoriety, they have proven themselves to be dangerous and entertaining in equal measure.
10. Time Wraiths
The Time Wraiths are some of the Arrowverse's more unsettling creations, acting as a reminder of what speedsters would face if they abused their abilities. Their purpose is somewhat similar to that of the Black Racer from the mainstream DC universe, and these beings are just as deadly and fear-inducing as their comic book counterpart.
The Dementor-like creatures are tasked with attacking careless time travelers as well as speedsters who break the rules of the Speed Force. This is done with the intent of preserving the proper flow of the timeline and the Speed Force's integrity.
Speedsters such as Barry Allen, Eobard Thawne, and Hunter Zolomon have all had near-fatal encounters with the otherworldly entities, with the latter being transformed into a version of the Black Flash that was forced to do the Speed Force's bidding.
It is unclear what became of the Time Wraiths following the Crisis on Infinite Earths crossover, though it is possible they perished along with the original Speed Force following its destruction.