Infinity Train is an American animated television series created by Owen Dennis. As of 2022, four seasons totalling forty episodes have aired, plus an additional series of ten short webisodes.

The series is set on a gigantic, mysterious and seemingly endless train traveling through a barren landscape, whose cars contain a variety of bizarre, fantastical, and impossible environments. Passengers on the train proceed from car to car by completing challenges which help them resolve their psychological trauma and emotional issues. Every season of Infinity Train (referred to as a "Book", each with its own separate subtitle) follows its own storyline and set of characters, although some characters appear across multiple seasons.

The pilot for the series was released by Cartoon Network on November 1, 2016, before being picked-up for a full miniseries due to positive reception, which premiered on Cartoon Network on August 5, 2019. After the conclusion of the first season, Cartoon Network announced that the series would continue as an anthology series. The second season debuted on Cartoon Network on January 6, 2020. The third season began airing on HBO Max on August 13, 2020, with ten episodes airing across three weeks, and the fourth season was released in its entirety on April 15, 2021. All four seasons of Infinity Train have received critical acclaim for their complex themes and characters, writing, uniqueness, visual animation style, and voice acting. In August 2020, Dennis stated that, although he wanted to continue the series for a total of eight seasons, most of the crew had been laid off and the series was at risk of not being renewed for a fifth season; Dennis suggested that HBO Max might be concerned that the series' stories and themes were too dark and unappealing to children. Promotional material for the fourth season refers to it as the final season of Infinity Train. In August 2022, the series was removed from HBO Max; in October 2023, the show was removed from digital purchase platforms.