The 31-year-old has played the super hero in movies like 'Fantastic Four', 'Fantastic Four: Rise of the Silver Surfer' and 'Captain America: The First Avenger'.
He got to know about Louis Campbell's death after reading a blog written by the boy's mother on his fight with the disease and his obsession with superheroes. The doctors had detected tumour at the base of the boy's skull when he was just 2-year-old, reports contactmusic.com.
Evans wrote on Twitter: "Sending my condolences to the family of Ty Louis Campbell, a brave 5-year-old boy who lost his battle with cancer. I only wish I heard about this warrior sooner. I would have loved to shake his hand."