Infinity Train

• Tulip Olsen (voiced by Ashley Johnson; Naomi Hansen (as a 5-year-old); Lily Sanfelippo (as a 6–8-year-old)) – A 13-year-old girl struggling with her parents' divorce who finds herself trapped on the train when trying to get to game-design camp. She is analytical, down-to-earth, and determined to get off the train.
• One-One – A spherical robot consisting of two separate hemisphere-shaped robots. In Book 1, One-One accompanies Tulip on her journey, and eventually learns that it is the rightful Conductor of the train. In Book 2, One-One has resumed its duties as Conductor, overseeing the operations of the train and passengers.
  • Glad-One (voiced by Jeremy Crutchley) – The exuberant and optimistic part of One-One.
  • Sad-One (voiced by Owen Dennis) – The morose and pessimistic part of One-One.
• Atticus (voiced by Ernie Hudson) – The talking Corgi king of Corginia, one of the train cars. He accompanies Tulip on her journey.

• "MT" (voiced by Ashley Johnson) – Tulip's reflection, freed from the mirror world by Tulip in Book 1. At the start of Book 2, she has been living on the train as a fugitive from the reflection police. She accompanies Jesse on his journey through the train while struggling with her sense of identity as an independent person, rather than Tulip's reflection or a construct of the train. Upon escaping from the train at the end of Book 2, she names herself Lake.
• Jesse Cosay (voiced by Robbie Daymond) – A passenger who becomes MT's friend and helps her escape the train. He is easygoing and friendly, but has a hard time standing up for himself and resisting bullies; his experience on the train teaches him how to stand up for his friends.
• Alan Dracula – A magical white-tailed deer who accompanies Jesse and MT.

• The Cat (voiced by Kate Mulgrew) – A talking cat who is a collector and con artist. In Book 1, she is an agent for Amelia; in Book 2, she runs a carnival. (Recurring Book 1; Guest Book 2)
• Amelia (voiced by Lena Headey) – A passenger who overthrew One-One and usurped his position as the Conductor, hoping to use the train to recreate her dead husband Alrick (voiced by Matthew Rhys). (Recurring Book 1)
• The Steward (voiced by Johnson) - A menacing robot that assists the Conductor. (Recurring Book 1; Cameo Book 2)
• Ghoms (voiced by Dee Bradley Baker) – Dog/cockroach-like creatures that inhabit the Wasteland outside the train and attempt to suck the life-force out of the living. (Recurring Book 1; Guest Book 2)
• Megan Olsen (voiced by Audrey Wasilewski) – Tulip's struggling mother and Andy's ex-wife who works as a nurse. (Recurring Book 1)
• Andy Olsen (voiced by Mark Fite) – Tulip's depressed father and Megan's ex-husband. (Recurring Book 1)
• The Reflection Police (a.k.a. "Flecs") – A pair of officers pursuing MT in order to destroy her for abandoning her responsibility as Tulip's reflection. (Guest Book 1; Recurring Book 2)
  • Agent Mace (voiced by Ben Mendelsohn) – The gruff senior partner of the team.
  • Agent Sieve (voiced by Bradley Whitford) – The more upbeat junior partner to Mace.
• Grace (voiced by Kirby Howell-Baptiste) – The leader of Apex, a gang of passengers who aim to raise their numbers to remain on the train indefinitely. (Recurring Book 2)
• Toad / Terrence (voiced by Dennis) – A toad originating from the Toad Car where the objective is for the toad to be kicked. (Recurring Book 2)
• Nathan “Nate” Cosay (voiced by Justin Felbinger) – Jesse's younger brother. (Recurring Book 2)

Guest voices for Book One include Rhys Darby and Ron Funches. Guest voices for Book Two include Wayne Knight, Laraine Newman and Bill Corbett.

Owen Dennis conceived Infinity Train in 2010, originally as a film. Like protagonist Tulip, Dennis created video games as an amateur in his teens, including point-and-click adventure games and mods for titles such as Half-Life 2 and Unreal Tournament 2004. He has stated that Myst has been one of his primary influences since he was 13, and its influence continued in Infinity Train.[6] He also cites Doctor Who, Agatha Christie, The NeverEnding Story, The Matrix, Philip K. Dick, Star Trek: Voyager, and Sliders as influences, along with novels such as Nightbirds on Nantucket and The Wolves of Willoughby Chase.[7]

The pilot was first released on the Cartoon Network App and VOD on November 1, 2016, and released the following day on the official Cartoon Network YouTube channel. The short garnered a million views within its first month of availability and has since gained 4.7 million views as of July 2019, making it the most viewed pilot on the channel while two other originals, Welcome to My Life is the second most viewed pilot, and Twelve Forever (later moved to Netflix) being the third most viewed pilot.[8] A petition to greenlight Infinity Train made shortly after the pilot was released garnered over 57,000 signatures before the greenlight announcement.[9]

On March 11, 2018, Cartoon Network's official website launched a teaser site that confirmed the short had been greenlit as a full series.[10] In July 2018, a sneak peek of the first season was revealed on the Cartoon Network panel at the 2018 San Diego Comic-Con. It was released a couple of hours later on Cartoon Network's social media platforms. A full trailer for Infinity Train was released in June 2019 which was unlocked by playing the show theme on the Infinity Train website. It was later uploaded to Cartoon Network's YouTube channel. On July 11, 2019, the show was confirmed to premiere on August 5, 2019.[2] On July 20, 2019, the first episode was shown during the Infinity Train panel at San Diego Comic-Con. It was then released on the Cartoon Network app and website later that same day.[11] The first season would be 10 episodes long, with two episodes airing each night from August 5 to August 9, 2019.[12]

A promo after the final episode of the season confirmed the series would return.[4] On November 22, 2019, the Infinity Train website was updated with a new claw machine puzzle. Completing the puzzle leads to a trailer for Book 2. The trailer was then released officially the next day.[13]

Book Two debuted on January 6, 2020.[14]

From October 18, 2019, Cartoon Network started uploading a series of Infinity Train shorts onto their app and YouTube channel called "The Train Documentaries", which focused on One-One showing off a number of cars in the train, including "The Green Car", "Tiny Wizard Car", "The Kaiju Car" and "The Tech Support Car".

Infinity Train received critical acclaim upon its debut. Caroline Cao of /Film declared it a "wild triumph",[16] while Nerdist's Andrea Towers declared it "one of the best animated programs of the year."[17] Reuben Baron of CBR compared it to Cartoon Network's animated miniseries Over the Garden Wall in its perfection, hailing it as "a beautifully handled piece of self-contained, character-driven storytelling."[18] Skyler Johnson from Comic Watch called it "excellent", with "emotional depth that is rarely seen in children's television", "witty, clever humor", and "stellar voice action."[19] Emily Ashby of Common Sense Media gave the series 5 out of 5 stars. In her review Ashby praised the positive messages about friendship and self-reflection. Ashby also praised the character of Tulip and the show’s emotional moments.[20]