GDThallium (Theaverageoffice on the Wiki, Thallium GoodDay on YouTube) is a Geometry Dash player. He is mainly on Geometry Dash-related Wikis.
- If Rebellion was L1(His most liked level, also his 1st lvl 1 level)
- If Flask was L1
- If Dark Nebula was L1
- Project Denominator (WIP mega-collaboration)
- Hop (WIP mega-collaboration)
- If Hi was L1
- The Massacre (set to be his first original solo level, WIP)
- A few other short levels testing out random effects
- He is a former staff of the Geometry Dash Fan Wikia.
- He changed his name to GDThallium as he felt that Theaverageoffice was too long. He got the inspiration from a chemistry lesson.
- He is known for uploading cut game-plays of extreme demons like Yatagarasu on YouTube.