It has not yet been confirmed who will play Thalia in the Sea of Monsters.
However, it is rumored by fans that Brenda Song will play Thalia.
According to Imdb, Kaya Scodelario is rumored to be playing Thalia Grace.
they will be held Sepember 24. 2010 in NYC i will be trying out for Thalia
Percy, Annebeth, Luke, Grover, Chiron, (all same actors) then for the new characters there is: Tyson (a cyclopes) and Thalia Grace.
Not exactly. Thalia appears towards the end of the episode due to the healing powers of the Golden Fleece. The Golden Fleece manages to restore Thalia's soul to her body, so , she is 'resurrected'
Thalia is Paloma Kwiatkowski
Thalia can opt to leave the hunters. This answer came from the Percy Jackson Wikia.
Thailia grace
Percy and Annabeth save Grover from Polyphemus in the Sea of Mosteres. Then they bring the Golden Fleece back to Camp Half-Blood to heal Thalia's Tree. But The Fleece's magic works to well and Thalia comes back.
Because someone was messing with his camp and poisoned Thalia's tree so monsters could come in. (it turns out it was Luke who poisoned it.)
It is unknown at the moment, but auditions have finished
Yes, Thalia will come in the second book, but only at the end.
Percy Jackson: Sea of Monsters.