Nightfall is a recurring character in the 2018 adult animated series Final Space.
Nightfall is actually a future version of former Infinity Guard agent Quinn. It is revealed in Chapter 7 that Nightfall was given that alias by her version of Gary who she is all but stated to be in a relationship with. It is revealed that Nightfall had traveled through multiple timelines which have all ended in tragedy. In her original timeline, her Gary was murdered by the evil Lord Commander. As a result of this, Mooncake becomes enraged and relentlessly destroys several planets in his rage; this in turn would release primordial extraterrestrial beings known as the titans who reside within Final Space itself. No matter the timeline she traveled to, the same result inevitably happened. Sometime before the start of the series, Nightfall apparently discovered the timeline the show takes place in, and for the most part, she assisted Gary in the shadows whilst keeping her eyes on Mooncake.
In Chapter 7, Nightfall formally introduces herself to the crew of Galaxy One, much to her past self's confusion and Gary's fascination. When she became acquainted with the team, she tried to prevent Gary from leaving with Mooncake by using energy cuffs to restrain him while she left to kill Mooncake. Nightfall comes dangerously close to exterminating the gelatinous lifeform only to be stopped by Gary and Quinn. To make matters worse, Little Cato and KVN become trapped in Nightfall's time ship when Little Cato tried to use it to travel back in time only to accidentally engage the self-destruction function. Nightfall manages to rip a hole into the ship informing Gary that he must get them both out due to the instability in time. After saving the two, Quinn convinces Nightfall to give Mooncake a second chance, which Nightfall allows despite her concerns.
Nightfall reveals in Chapter 8 that she encountered a benevolent Titan named Bolo when she was close to committing suicide. Bolo had been imprisoned within a giant cube for thousands of years after he rebelled against his fellow Titans and sealed the portal to Final Space. However, Galaxy One had to pilot through a sun in order to get to Bolo's dimension. After she watched a rendition of Gary's father sacrificing himself in order to close the breach to Final Space, she decides to leave, concluding that they no longer need her assistance.