Former Heroes star Thomas Dekker has lashed out at ex-castmate Milo Ventimiglia for dating pretty teen Hayden Panettiere, calling the romance "gross".

Dekker, who is now the star of Terminator TV spin-off The Sarah Connor Chronicles, played 18-year-old Panettiere's best friend in the first season of the sci-fi phenomenon. And he can't believe 30-year-old Ventimiglia is dating a girl almost half his age.

The outraged actor, 20, tells Life & Style magazine, "I think it's gross, to be perfectly honest. It's kind of like if I were dating a 12-year-old! I'm definitely surprised they're together. For me, it would be a struggle to be with someone in such a different age range."