The Time Baby is the last son of an extinct race of time giants, and weighs approximately nine trillion tons. At some unknown point in the past, the Time Baby was frozen in an Antarctic glacier. According to the Northwest Cover-up, the statues at Mt. Rushmore are actually robots to be called into action to fight the infant upon his release. At some point in the distant future, he is freed due to global warming and wreaks havoc on human civilization, ultimately overpowering all opposition and ascending to global domination.
After Dipper and Mabel Pines compromise Time Anomaly Removal Crew agent Blendin Blandin's mission in Gravity Falls, Oregon in "The Time Traveler's Pig," the Time Baby blames the operative for the incident, sends him to remove them, and then sentences him to "ten squared" lifetimes in the Infinetentiary. When Blendin escapes and invokes Globnar against the Pines twins in "Blendin's Game," the Time Baby presides over the match and carries out the twins' requests when they win the battle, as well as providing them with a time wish.
In "Weirdmageddon Part 1," he appears with the Time Police to arrest Bill Cipher for possessing Blendin Blandin. As he threatens to throw a tantrum, Bill easily vaporizes him and the time police. The cryptogram during the credits reveals that it will take 1,000 years for him to reconstitute his molecules.
In "Weirdmageddon 3: Take Back The Falls," he was mentioned by Bill, who referred to him as "that dumb baby."
The Time Baby is approximately the size of a small building, has a glowing blue hourglass mark on his head (red when attacking the city), and black eyes. When he is shooting a laser from his eyes, the eyes turn red. His head is bigger than his body, with pink blush on his cheeks and long eyelashes. He is half nude, bearing only a diaper.
- It is stated that the Time Baby is "worried about Bill," and, according to Bill himself, Bill wishes to destroy Time Baby, so he is obviously worried what Bill will do to him.
- Time Baby is easily distracted by jingling keys.
- It was stated by Alex Hirsch that "Time Baby and Bill do not like each other, if they saw each other at a party they would be doing that 'awkward circle thing' where they're making eye contact but they're not talking to each other and everybody's like 'Do they know each other? Do they have a history?'." He also said that, "Given the chance, Bill would be a terrible babysitter to Time Baby."
- Time Baby's voice actor was uncredited until "Weirdmageddon Part 1."
- Along with Alex Hirsch, Time Baby "hosted" the behind the scenes special Between the Pines.
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