IT

NOTE: IT will not be referred to with words like he/she, as it's gender is random.

It (Referred to as IT, or Pennywise) is an ancient alien/eldritch monster and the title character and main antagonist of the 1986 novel the same name (and subsequent television and film adaptations). It is a shapeshifting creature known as a Glamour and is billions of years old. Although it lived on planet Earth for many years, it originated in a void/dimension outside the regions of space known as the Macroverse. Since its true identity is unclear, due to its shape-shifting abilities making its real name and species unknown, the creature is just named IT.

Why IT Rocks (No Pun Intended)

 * 1) IT is one of Stephen King’s most diabolical and memorable antagonists.
 * 2) It’s expressions and characteristics are ungodly and unpredictable, showing how terrifying IT can be.
 * 3) It takes many forms of people’s worst fears, mainly it’s most memorable form, Pennywise the Dancing Clown.
 * 4) Actors Tim Curry and Bill Skarsgard did fantastic jobs at portraying a live-action version of Pennywise, giving Skarsgard a starting point for IT's portrayal.
 * 5) IT steals the show most of the time with It’s goofy yet frightening  behavior as Pennywise, such as the Pennywise Dancing moment.
 * 6) Has many memorable quotes, such the unforgettable “You’ll all float down here.” line.
 * 7) It’a gender, whereabouts and origin are hidden with the a deadly ball of lights known as the Deadlights, showing it truly remains a mystery, making it even more of a terrifying figure.

Bad Qualities

 * 1) In the 2017 movie, it is implied that IT wasn't malevolent by nature, but rather just looking for its favorite foods, which contradicts the lore of King's novel and the fact that It is confirmed to be pure evil by Bill Skårsgard himself.
 * 2) While its 1990 design is pretty terrifying, it makes It look a lot more like a children's clown at a birthday party, in comparison to his 2017 counterpart, the 2017 design looks to scary to trick the kids (in the movie) as in the original for the clownish behaviour.

Trivia
This would make Pennywise the only Stephen King villain to be still alive.
 * Though It was believed to be deceased by the end of the book and miniseries and IT: Chapter 2 where It was killed, the first line in the book implies that Pennywise may have possibly survived. This seems likely as Pennywise is referenced to in a few of Stephen King's other novels. These could set up for another book, however, in a recent King Reddit QA, he claims he doesn't have any plans to write one.
 * One instance is in Tommyknockers (1987) when Tommy Jacklin goes to Derry on a supply run and thinks he sees a “clown with shiny silver dollar eyes” watching him from the sewers.
 * Another instance is in DreamCatcher (2001) when Mr. Gray sees the plaque meant to remember the victims of Derry when the water storage standpipe was destroyed. Spray painted over the plaque are the words "PENNYWISE LIVES."
 * Of the thirty-two forms It takes in the novel, fifteen are recreated in some way, shape, or form in either or both the 2017 and 2019 films.
 * The Crimson King is believed to be of the same species as the monster, IT and he may be the son of the crimson king, however this was unofficial.
 * Though likely, it's unknown if It killed Peter Gordon, Moose Sadler and Gard Jagermeyer.
 * It is unknown what is Pennywise's real name, making him possibly nameless.