Supreme leader of Sikhism is the Guru Granth Sahib. Guru Grant Sahib is a holy book, and it is the final Guru (teacher) of the Sikh religion. The first ten Gurus, along with the 1st Guru (Guru Nanak) the founder of Sikhism, were people. And since the death of the 10th Guru (Guru Gobind Singh), the holy book Guru Granth Sahib is considered as the only Guru/teacher of the Sikh religion, since Sikhism doesn't have priests - everyone is equal.
guru
Ofcourse he is.
Guru Ji
Guru
Aristotle was his teacher... However, I am not sure this is the answer you are looking for...since a guru is a spiritual leader... and Aristotle clearly wasn't a spiritual leader..
The leader of Sikhism is Guru Gobind Singh Ji.
There is no leader of Sikhism currently. But Sikhs call their leaders "Guru". The first Guru who formed Sikhism was called Guru Nanak
Guru
The Sikh Holy book is considered as the Immortal Guru / Teacher after the 10th and the last Guru, i.e. Shri Guru Gobind Singh Ji and He said, after me this will be your Guru. Consider this is Me, not mere a book. So, sikh society, as directed, considered the Holy book as Guru and abide by the thought that a Guru / Spiritual Leader woke up early morning and same time give respect while HE sleep, where no noise, only cleanliness and peace.
The purpose of following guru is u have to follow hats goin to happen about the guru
He knows so much about computers we call him a guru. Gandhi was considered a guru.