Thaddeus the Beard Guy, also known as Beard Guy, Beard, or Not David is a mysterious nameless friend of FMB. It is unknown if he plays any role in the production of Voltz Wars as he has been described as 'not from YouTube'. He is jokingly listed as the voice of D_47the_avid.
Thaddeus' real name remains unknown. He was given the name 'Thaddeus the Beard Guy' during FMB and FnD's meetup video. When professing he wants to remain anonymous, Rob suggests 'Beard Guy', Richard suggests simply 'Beard' and David suggests 'Thaddeus' for his pseudonym. These are eventually combined into 'Thaddeus the Beard Guy'. However, Thaddeus himself states he prefers to be called 'Not David'.