He died a few days ago, but his funeral was held today. He is well known for his alleged connection to the 2016 Turkish coup attempt. He is well known to have aided in impeding the leftist movements in Turkey and supporting the Islamist AK Parti in taking power and displacing Turkish secularists. His movement has also been alleged to have received funding from the NED as part of the US's "Green Belt" project, an initiative to prop up Islamist anti-communist governments in the Middle East during the Cold War to counteract the influence of the USSR and the Eastern Bloc. He has also been known to pander to Zionists, notably opposing the flotilla delivering aid to besieged Gaza in 2010.
His history and the atrocities linked to him could fill up a book (and there are many books about him), but he's relatively unknown outside of Turkey.