The noun God is the proper English name used for the deity of monotheistic faiths. Different names for God exist within different religious traditions:

Allah is the unique name of God used in Islam, and also by most non-Muslim Arabs. ilah, cognate to northwest Semitic El, is the generic word for a God (any deity), Allah contains the article, literally "The God". Also, when speaking in English, Muslims often translate "Allah" as "God". One tradition states that Allah has 99 names.
Yahweh Hebrew: 'YHVH' (יהוה), and Jehovah are some of the names used for God in various translations of the Bible (all translating the same four letters - YHVH). El, and the plural/majestic form Elohim, is another term used frequently, though El can also simply mean god in reference to deities of other religions. Others include El Shaddai, Adonai, Amanuel, and Amen. When Moses asked "What is your name?" he was given the answer Ehyeh Asher Ehyeh, which literally means, "I am that I am," as a parallel to the tetragrammaton YHWH. See The name of God in Judaism for Jewish names of God. Most Orthodox Jews, and many Jews of other denominations, believe it wrong to write the word "God" on any substance which can be destroyed. Therefore, they will write "G-d" as what they consider a more respectful symbolic representation. Others consider this unnecessary because English is not the "Holy Language" (ie, Hebrew), but still will not speak the Hebrew representation written in the Torah, "yih-yah", aloud, and will instead use other names such as Adonai (my lord).
The Holy Trinity (meaning the Father, the Son (Jesus Christ), and the Holy Spirit/"Holy Ghost") denotes God in almost all mainstream Christianity. Arab Christians will often also use Allah to refer to God.
God is called Igzi'abihier (lit. "Lord of the Universe") in the Ethiopian Orthodox Church.
Jah is the name of God in the Rastafari movement.
The Maasai name for "God" is Ngai, which occurs in the volcano name Ol Doinyo Lengai ("the mountain of God").
The Mi'kmaq name for "God" is Niskam.
Some churches (United Church of Canada, Religious Science) are using "the One" alongside "God" as a more gender-neutral way of referring to God (See also Oneness).
Ishvara is the term used for God among the Hindus. In Sanskrit, it means the Supreme Lord. Most Hindus worship the personal form of God or Saguna Brahman, as Vishnu, Shiva, or directly as the Supreme Cosmic Spirit Brahman through the Gayatri mantra. A common prayer for Hindus is the Vishnu sahasranama, which is a hymn describing the one thousand names of God. Ishvara must not be confused with the numerous deities of the Hindus. In modern Hindi, Ishvara is also called Bhagavan.
Baquan is a phonetical pronunciation for God in several Pacific Islander religions.
Buddhism is non-theistic: Instead of extolling an anthropomorphic creator God, Gautama Buddha employed negative theology to avoid speculation and keep the undefined as ineffable. Buddha believed the more important issue was to bring beings out of suffering to liberation. Enlightened ones are called Arhats or Buddha (e.g, the Buddha Sakyamuni), and are venerated. A bodhisattva is an enlightened being that has chosen to forego entering into nirvana to help others to become enlightened, though there is no reason for there to only ever be one, and no reason that any ordinary human may not become a bodhisattva. Buddhism also teaches about the devas or heavenly beings who temporarily dwell in states of great happiness.
Jains invoke the five paramethis: Siddha, Arahant, Acharya, Upadhyaya, Sadhu. The arhantas include the 24 Tirthankaras from Lord Rishabha to Mahavira. But Jain philosophy as such does not recognize any Supreme Omnipotent creator God.
Sikhs worship God with the name Akal (the Eternal) or Omkar (See Aum). Help of the gurus is essential to reach God.
In Surat Shabda Yoga, names used for God include Anami Purush (nameless power) and Radha Swami (lord of the soul, symbolized as Radha).
Ayyavazhi asserts Ekam, (The Ultimate Oneness) as supreme one and Ayya Vaikundar the Incarnation of Ekam. There are also several separate lesser gods who were all later unified into Vaikundar.
The Bahá'í Faith refers to God using the local word for God in whatever language is being spoken. In the Bahá'í Writings in Arabic, Allah is used. Bahá'ís share some naming traditions with Islam, but see "Bahá" (Glory or Splendour) as The Greatest Name of God. God's names are seen as his attributes, and God is often, in prayers, referred to by these titles and attributes.
Zoroastrians worship Ahura Mazda.
Kisaski, Japanese God incarnate.