The most important thing is, the monsters are sent by people. Terrible people! That's why I built Mech-X4. So you could stop them, Ryan.

Leo Mendel is the creator of Mech-X4. His current location is unknown, but he's revealed to be alive and held hostage. He left various video messages behind for the boys to discover, but they have yet managed to find out who he really is.


Leo was the one who created Mech-X4 some time prior to the events of Let's Call It Mech-X4!. He has warned that the Mech-X4 team monsters are coming and that Mech-X4 was built to defend the city. He knew that Ryan was a Technopath since birth, and that he'd be the one to discover Mech-X4. For Ryan's safety, he anonymously put him up adoption. It's shown in Let's Get Some Air!, he is being held captive by the creator of the monsters, who is later found out to be Seth Harper. It is also revealed he built a failed prototype of Mech-X4 called Mech-X3, which was piloted by Leo OS and was scavenged for parts in the second half of season one.


  • He is the only person who knows about Ryan's past and the development of his powers.
  • He is the only adult on the Mech-X4 crew.
  • His last name comes from Mendel's Genetic Laws in Biology.


Season 1

Season 2


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To view the Leo Mendel gallery, click here.

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