All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
According to the scholars it was Hamzah ibn 'Abdul-Muttalib who was nicknamed ‘the Lion of Allaah’; we already explained this in Fatwa 87558.
When the above name is mentioned, it refers to Hamzah . However, there are many ‘lions of Allaah’, who fought for the sake of Allaah The Almighty, and there is no doubt that 'Ali was one of them. He was known for his bravery and strength, but the above expression (i.e. ‘the Lion of Allaah’) does not refer to him but to Hamzah as we already mentioned.
For more information on the excellence and virtues of 'Ali please refer to Fatwa 84903.
Finally, it should be noted that such a matter should not be a reason for disputes.
Allaah Knows best.