Three

a.k.a. Threefolder

Co-lead developer of PlatinumQuest.
Best known as a level creator. Generally considered one of the greatest of all time.
Added to the Marble It Up! team as a level designer for Marble It Up: Mayhem!

Joined the community in 2008, and made his first post in 2011.
Creator of Marble Blast Revived, a noob mod released in 2011 to mixed reviews. He also created Marble Blast Revived 2 which was also released after being dead for a couple years.
Worked on Project Marbles, a marble game started by Jeff and co-created by Whirligig. Took a hiatus from the community after this game fell apart, only returning to regularly releasing custom levels in early 2015.
Joined the Platinum Team as a level designer in September 2015 following a long streak of high-quality custom levels, and was later promoted to lead developer.
Became more active in the Marble it Up! community than in the Marble Blast community upon the former game's PC release in November 2018.
One of the contributors to this site.

Fighting Whirligig for the title of resident furry. His older otter fursona manifests itself in many popular avatars and emojis in the community.
For April Fool's Day 2018, the official Marble Blast discord was turned into the "Threefolder Fan Club," where every user's nickname was changed to riff off his own, and the only custom emojis allowed to be used were of his fursona.
Turned 18 in 2017. The phrase “Threefolder are you 18 yet”, having originated with Uil, had become a ubiquitous meme in the community for years prior, and still survives to this day in different forms (e.g. NF are you 18 yet).
Commonly associated with salt.
Well known for blocking off shortcuts in his levels by any means necessary.

Rink Ring, a PQ level by Three.

Jaunt, a MIU level by Three.