Islam, that means in Arabic peace and submission to the one and only one God, is the call of all God prophets (including Noah, Abraham, Moses, Jesus, and Muhammad) for people since start of mankind.
So, if the question talks about Islam in this sense, then all God prophets are founders of Islam.
However, as Judaism and Christianity are religions per God revelation of respectively Torah and Bible to respectively the prophets Moses and Jesus, the very name Islam is the religion per God revelation of Quran to the prophet Muhammad.
So, if the question talks about Islam religion per God revelation of Quran to Prophet Muhammad, then he is the only founder of Islam religion per the holy book Quran and his teachings (sayings and practices).
The religion?
God is the founder of Islam. Refer to question below.
Christianity was founded by Hazrat Jesus Christ (May peace be upon him). Islam is founded by the last prophet of Islam Hazrat Muhammad (SAW).
None Allah (God in English) is the founder of Islam before prophet Muhammad (PBUH) and after him. Refer to related question below.
Christianity and Islam are the ONLY religions having this understanding.
It would be helpful if you were to tell us which founders you are asking about; many different people have founded many different things, in the course of human history. Possibly you mean the founders of America, in which case the answer is, the religion of the founders was Deism.
Islam is an Arabic word that means submission to God and surrender to His will. Allah (God in English) is the Islam founder since start of universe creation, Refer to question below for more information.
Salafiyya: "The way of the founders", reactionary Islamic puritanism and the basis of current Islamism.Ref:Roskin, M. G., & Berry, N. O. (2010). IR: The New World of International Relations, Eighth Edition. Longman.
Judaism and Islam are based on the same foundations and ancient texts, funny huh?
Allah (or God in English and same God worshiped in Christianity and Judaism); the Creator; is the founder of Islam. Refer to related question below.
The possessive form of the plural noun founders is founders'.Example: We have a bronze plaque with our founders' names.
The top 6 religions in the world are Christianity, Islam, Hinduism, Buddhism, Sikhism, and Judaism. They originated in different parts of the world - Christianity in the Middle East, Islam in Arabia, Hinduism in India, Buddhism in Nepal/India, Sikhism in Punjab (India/Pakistan), and Judaism in the Middle East.