Tim Tomorrow lives on Earth-54, an alternate universe where the Earth spacefaring begun earlier than in our world. He is Tommy Tomorrow's young brother. He wants to become a Planeteer when he grows up, and after an adventure along his brother, he is made a honorary member of the organization.
- This version of Timothy Tomorrow (Earth-54), including all history and corresponding appearances, was erased from existence following the collapse of the original Multiverse in the 1985–86 Crisis on Infinite Earths limited series. Even though versions of the character may have since appeared, this information does not apply to those versions.
- Tommy Tomorrow was regularly featured in back-up stories in Action Comics.
- Crisis on Infinite Earths: Absolute Edition established that some of Tommy Tomorrow's adventures happened on Earth-54 given they happened in the 20th century while the later stories were set in the 21st century.
- 2 Appearances of Timothy Tomorrow (Earth-54)
- Images featuring Timothy Tomorrow (Earth-54)
- Quotations by or about Timothy Tomorrow (Earth-54)
- Character Gallery: Timothy Tomorrow (Earth-54)