Conversation so far:
What was James Dean's first job?
Dean's first television appearance was in a Pepsi Cola commercial.
Did James Dean have any other television appearances besides the pepsi commercial?
Yes, he appeared on TV from 1951-1955.
When was James Dean casted in his first speaking part?
His first speaking part was John the Beloved Disciple, in Hill Number One, an Easter television special dramatizing the Resurrection of Jesus.
Did James Dean act in movies early in his career?
His first film role was in the 1951 film Fixed Bayonets!

Question: what role did he play in Giant?
Self-contained rewrite: What role did James Dean play in Giant?