The 26-year-old actor, who is best known for his long standing lead role as the iconic wizard Harry Potter, said he was petrified of Fiennes, for years, reported Female First.
"Ralph genuinely scared me for a few years. I remember when I was 15 doing scenes with Ralph for the first time. He was even scarier than Alan was at first," he said.
The star has also revealed that he was also super intimidated by the actor Alan Rickman, who passed away in January this year aged 69 and played Professor Snape.