Writing on her Twitter page, series writer and actress Mindy Kaling announced the process behind the choice of names for the stars, who will turn up in the NBC comedy's season finale later this year.
Catherine Tate, Ray Romano and James Spader will appear alongside previously announced guest Will Arnett in the two-parter due to air next month.
"Naming new characters is one of the most fun times in a writers room... Takes a tiny, silly part of the brain! (sic)" Kaling wrote.
"William Arnett plays 'Fred Henry', Raymond Romano plays 'Merv Bronte', and James Spader plays 'Robert California'. These are real, guys. Catherine 'The Great' Tate is Nellie Bertrum. (Again, real.)"
All besides Romano are said to be in the running to replace Steve Carell, who will exit during an extended episode later this month.