Buddha Vajradhara is thought to be the supreme essence of all Buddhas. He is an expression of Buddhahood itself in both single and yab-yum form. Buddha Vajradhara is considered to be the prime Buddha of the Father tantras (tib. pha-rgyud) such as Guhyasamaja, Yamantaka, and so on.
Property of Balbar Lama (Buryatia) Russia