Blue is a secondary colour of The Yellow Mythos as the Pallid Mask is sometimes pictured with a blueish tint and the Pleiades stars are blue. In Fungi From Yuggoth, the rays emitted by the Elder Pharos are blue. It is also mentioned in implied connection with the Pallid Mask in the poem Strange Words. In a non-mythos setting, blue is the colour of the Blue Room imprisoning Ksarul, a being similar to The King In Yellow. As a colour of putrefaction, it would be suitable for certain interpretations of the mythos.
Blue has associations with sadness and the sombre. A significant development of these associations was Picasso's Blue Period. This period was in part influenced by the suicide (instigated by unrequited love of a model), in Paris, of a friend and fellow artist, and happens to include a work titled 'The Blue Room'.