But, speaking to Jonathan Ross, the former child star revealed that she was heartbroken because her love for the young actor - who played naughty Draco Malfoy - was unrequited.
She said: "Between the ages of 10 and 12 I had a crush on Tom. I used to go into work in the morning and look at the call sheet to see if he was going to be in every day. He was a bad guy, a few years older than me, and had a skateboard and that did it for me.
"He totally knew but said he only saw me in a sisterly way and that broke my heart."
But Emma scotched rumours that she'd had a romance with her other co-stars Daniel Radcliffeor Rupert Grint.
She continued: "There was no romance between me and Daniel or Rupert. The whole 10-year period I never so much as pecked one of them on the cheek.
"Rupert gave me a beaver when we all left. He sponsored a beaver for me for a year."