I have written before about Gyani Balkar Singh,our Punjabi teacher in school, who taught and told us many things beyond textbooks.
During one of his lectures in the class, he told us about BHAI MARDANA, who became a disciple and companion of Guru Nanak during the Guru's journeys through India and Asia.
It is common knowledge that Mardana was born to Muslim parents who lived in Rai Bhoin Di Talwandi the same place in today's Pakistan where Guru Nanak was born. As for the name Mardana , there is an interesting anecdote that our teacher told us. The mother of Mardana remained sad and worried as all her children died sooner or later. It is said that she used to call this son also Marjana, as she believed that he would also die like his other siblings because of a curse that was purported to have befallen the family.It is said that Guru Nanak asked for her son to be given to him to which the mother agreed. Guru Nanak named him MARDANA which when split sounds Marda- Na which means 'won't die'. The family was thus saved from the curse of early deaths . Mardana not only became the first person to enter the Sikh sect, but also lived long and into his seventies.
Wikipedia also has the same story albeit with some twist. However the basic fact remains the same.