Who is the pope of islam?

Islam doesn’t have a big leader now which is accepted by the majority. In the past, a caliph was a huge leader in most times there was a caliph, but the Ottoman Empire did had the last caliph.

Shias does have the Ayatollah as pope and some shias does have Moqtada al-Sadr as the pope.

Houthis doesn’t have a big leader yet, but that can happen on short term.