Plex is a magical yellow robot who is treated like a male, the oldest, and one of the main characters in Yo Gabba Gabba!, being the first of DJ Lance's original creations before he goes through the main characters like Muno, Foofa, Brobee, and Toodee. He has no realm in particular, though he seems to have a "docking station" between Foofa Land and Brobee. Plex is no stranger to learning how to drive a car, using his special ray to bring things into existence, transporting living things, and stretching his arm super long to grab things from afar. Plex can even skateboard too. He's the band’s keytarist, which fits him well with the keytar (a guitar and a piano mix). His hobbies are driving his car, beaming things, playing his keytar and stretching his arms. He also has a niece named Plexee.
Plex is bright yellow, with a cylindrical torso, and yellow, somewhat blocky, hands and feet. He has a cylindrical, flat head with a large red antenna on the top, (which in fact was supposed to be blue during the Pilot episode,) and additional antennas on both sides of his head. His arms and legs are a shiny silver metal, which is flexible, unlike the rest of his body. His chest has a built-in speaker, and below that is a compartment which he uses in the show as a storage for various items, though it sometimes opens to reveal his inner workings as well.
He is portrayed as being intelligent, clear-spoken, well-educated with a clear attitude and the main leader of Gabba Land that often teaches lessons to his friends and is a father figure. Like an older brother, he knows how to solve problems that arise. When trouble arises with his friends, he is always there to teach them a lesson and be nice. This robot is also filled with many wonders and magical powers, being able to play music from his speakers. Plex also has a gentle and close connection to Toodee throughout most of the series, even during Mystery he tries his best to comfort her when she was afraid of the dark; so there is some dynamic contrast between the two.
- Plex, alongside Foofa and Toodee, was made exclusively for Yo Gabba Gabba!
- The costume character of Plex had three costumes throughout the show, and one during the live shows
- Plex's line of voice actors is very small, but his main voice actor is actually one of the co-creators of the show, Christian Jacobs. Costume performers for him include Lindsey Kraus (Series 0 - Series 2), Christian Jacobs (Series 0 - Series 4), Amos Watene (Series 2 - Series 4 - Present), and Lori Coulis (Series 3-4 Present)
- Plex is the only character that never read Super Martian Robot Girl in season 1.