It's the entity that caused so much trouble throughout the Paranormal Activity franchise, but what exactly is Toby? The original Paranormal Activity was a micro-budget found footage movie from director Oren Peli. The movie follows a couple named Katie and Micah who set up cameras around their home when they suspect they're being haunted, and the movie milks a lot of tension from this simple premise. Paranormal Activity became one of Blumhouse's earliest movies and while the initial plan was to remake it with a larger budget once it was picked up by Paramount, a hugely successful audience screening convinced them otherwise.
Paranormal Activity was re-edited for its theatrical release and a new ending was shot, with Steven Spielberg himself suggesting the final jump scare where a possessed Katie lunges at the camera. The movie became a massive success and soon kicked off a long-running franchise that dethroned the Saw series at the box-office. Subsequent sequels expanded the mythology, exploring Katie's backstory, with prequel Paranormal Activity 3 revealing how the demon first made itself known with Katie's young sister Kristi dubbing it "Toby." Like with most horror franchises the sequels were a mixed bag, with the third movie and spinoff Paranormal Activity: The Marked Ones considered the best, while the last entry Paranormal Activity: The Ghost Dimension was regarded as a disappointment.
The series also received a Japanese spinoff with 2010's Paranormal Activity 2: Tokyo Night, though the events of that film have never been mentioned in the rest of the series. While Paranormal Activity's Toby isn't a horror icon like Halloween's Michael Myers or Jason Voorhees, he made for a memorable villain. The backstory behind this entity is that Katie's grandmother Lois made a deal with a coven of witches for wealth and power in exchange for a demon taking the soul of her family's first-born son. Paranormal Activity's Toby has to wait a long time for a male to be born into the family, though he first makes himself known to Katie and Kristi when they are children in 1988.
Paranormal Activity 2 - which is set at the same time as the original - is set in Kristi's home, with Toby coming to collect her newborn son Hunter. Kristi's husband feels their only way out of trouble is to transfer the demon to a blood relative - in this case, Katie. This backfires spectacularly when Toby takes possession of Katie, killing Micah and in the finale of part two, killing Kristi and her husband before taking their son and disappearing. Paranormal Activity: The Marked Ones shines a light on what happens to the first-born males, with the witch coven helping a demon create an army of possessed men. The movie also ends by traveling back in time to the end of Paranormal Activity, where Katie kills her husband.
Paranormal Activity: The Ghost Dimension reveals Toby's ultimate goal is to take physical form, and the film gives viewers glimpses of the entity throughout. The film ends with Toby actually succeeding in this goal, though only his feet are shown. The sixth film was supposed to mark the end of the series, but a seventh entry is now in development. While it's possible the new movie could be a reboot, the more likely outcome is the next Paranormal Activity will be catching up with Toby and his antics following the events of The Ghost Dimension.