SUMMER Glau is known for playing extraordinary characters: brainy, deadly, not much like anyone you'd meet in the real world.

In Joss Whedon's beloved space adventure series Firefly, she was the damaged, precocious River Tam, forced by the evil Alliance to serve as an invincible assassin. In Terminator: The Sarah Connor Chronicles, she was Cameron, a cyborg sent from the future to protect the young hero. Then there was her eerie turn on Dollhouse, the most divisive but fascinating of Whedon's shows, where for a change she played a programmer rather than one of the programmed: the vengeful scientist Bennett Halverson, responsible for implanting personalities in ''dolls'' who agree to have their minds temporarily wiped.

Summer Glau: "I'm getting to say thank you to people." Credit:Philippa Hawker

Glau, 30, has become a cult figure among science fiction fans - and a regular at conventions such as the Supanova Pop Culture Expo, to be held this weekend in Melbourne and next weekend on the Gold Coast.

''It's a real honour,'' she says by phone from the US. ''I feel grateful to have these conventions to go to for a million different reasons, but one of the main reasons is that I'm getting to say thank you to people who have supported my career.''