Adi Shankara has said that there is only one Supreme Para-Brahma and all the other deities are the forms and expansions of this Para-Brahma. Under terms of some schools of Vedanta, It has three modal aspects with a highest as Para Brahma or Vishnu or Shiva or Harihara. This term is often used in relation to Vishnu or Shiva as the ultimate goal of Vedanta.
Para Brahma (Sanskrit, from para beyond + Brahma (neuter) universal self or spirit), or that which is beyond Brahma, is the self-enduring, eternal, self-sufficient cause of all causes and the essence of everything in the cosmos.
raso vai sa, rasam hy evayam labdhvanandi bhavati
The One is Bliss.
When there is no universe, Static Para Brahman appear in the dynamic form "Adi Shakti", from which universe is created and thereafter, Adi parashakti manifests herself in feminine form like Goddess Durga, Goddess Lakshmi and Goddess Saraswati.
You can never think of the one without the other.
nityo nityanam chetanas chetananam eko bahunam yo vidadhati kaman
All incarnations are either plenary portions or expansions of plenary portions appearing in various universes to protect the theists; but Lord Krishna is the original supreme lord and the source of all. (Bhagavata Purana 1.3.27-28) 
Lord Krishna is the supreme absolute controller, whose form comprises immortality, omniscience, and bliss. He is without beginning, the origin of all, the cause of all causes and the source of the Vedas. (Brahma Samhita 5.1) 
Let me offer my humble obeisance unto Lord Vishnu, who is the worship able deity for all brahminical people, who is the well-wisher of the cows and brahmanas and who is always benedicting all the universes. (Vishnu Purana 1.19.65) 
bhajagovindam bhajagovindam govindam bhajamuudhamate naamasmaranaadanyamupaayam nahi pashyaamo bhavatarane
Worship Govinda, worship Govinda, worship Govinda, Oh fool! Other than chanting the Lord's names, there is no other way to cross the life's ocean. (Bhaja Govindam, composed by Adi Shankaracharya) 
Narayana is, Para Jyoti, the greatest light, Para Atma, the super soul (Paramatman), Para Tatvam, the best of essences, Para Dhyata, the greatest meditator, Para Dhyanam, the best of meditations. (Narayana verse 4)
Govinda, is the primeval Lord, whose effulgence is the source of the nondifferentiated Brahma mentioned in the Upanishads, being differentiated from the infinity of glories of the mundane universe appears as the indivisible, infinite, limitless, truth. (Brahma Samhita 5.40) Shiva and Shakti philosophy
Shiva, who is Parameshwara (The Transcendent Lord), who is Satchitananda, issued Shakti. Shakti is not coexistent with Parameshwara but is that Power of Him that is necessary for creation. Shiva and His Shakti are more than the creation which He/She manifests. Shakti, who is the first desire (Kama) of Shiva, is Herself the Divine Mother of the cosmos. When the diverse cosmos emerged from Shiva's Shakti, the original desire that is the Primordial Will to be pervaded all manifestation. Microcosmically and macrocosmically, as above so below, all is Shiva/Shakti.
We can therefore say that the cosmos is the eternal undiluted Supreme Self expressed expansively from the central core that is Shiva/Shakti, thus enabling the Supreme Self to know, see, and live the Supreme Consciousness through its own self-willed limitation. By so doing the Divine Mother brings forth the stream of Truth embedded consciousness, later expressed as divine law, which is capable of recognizing Her as its primordial source. The cosmos, through this knowing of its source, unites with its Mother in the process of fulfilling the Great Work - Dharma. The penultimate purpose of the cosmos is mergence of the created drop with the ocean that is its Mother. This union is freely achieved within the constraints of Divine Law, brought forth by self limitation of the limitless light that Shiva/Shakti is. The pulsing throb that propels this eternal drive, this thrust for union, is AdiShakti, the Divine Mother as nature. She assumes this mantle without individuality, for She is the equal only of Herself as the silent witness within Her core, and She labours incessantly, through all of Her finite rays of light that define the cosmos, in conscious activity so that they, Her children, may become aware of themselves and merge in the ocean of self realized bliss.
All that is within all universes pre-exists within the Mother, for nothing can manifest that is not previously existent within Her womb. All evolution being directed towards perfection is the direct result of an innate knowing, a blueprint of limitless possibilities, brought forth by that which is resident within Shiva. This Principle precedes the expression, for without the Principle there can be no expression of its Will. Something does not emanate out of nothing. Other uses
Hindu sects like Vaishnavism, Shaivism and Shaktism have concept of ParaBrahma. However, in contrast with Vaishnavism where ParaBrahman denotes Saguna Brahma as Hari or Vishnu, either Saguna Brahman or the impersonal Nirguna Brahman may be connected by other sects. It is also customary that followers of a particular sect view other personal forms of God as expansions or aspects of the Supreme Being.