~Six (BFB)~

He is a Arabic numeral six (6), his body is sky-blue and his limbs are a lighter color than his body.

Six did not have a strong defined personality until "Thanks for 900,000 subscribers!". Before then, Six was shown to be somewhat antagonistic to Seven even before Seven kicked them out of the sub count, as they took despicable happiness in laughter when Seven was crying due to not being in the Sub Count in "Thanks for 600,000 subscribers!". They are shown to have a malicious side, such as kicking Seven and agreeing to kick out Eight.

In "Thanks for 900,000 subscribers!", Six appears to be somewhat irritable but also knowledgeable, as they knew that Seven's "ears" were squishy and that was how they were able to kick Seven. However, she is also quite friendly when interacting with Nine. Though this does not extend in helping others in trouble from their fellow kind, as they viewed Pie being attacked by Pi in "Pie Vs Pi: The Pi Day Massacre" as not their (referring to them alongside Two and Eight) problem.