When discussing celebrities, there are a few important words and phrases to keep in mind.

1. grande

i.e. ator / atriz / cantor / cantora / artista (actor, actress, male singer, female singer, artist)

Even though grande means big in some contexts, in this context it means great.

Kate Winslet é uma grande atriz, e já ganhou o Oscar. Kate Winslet is a great actress, and has won an Oscar.

2. trabalhar muito

This means that someone is really good at what he/she does, and is frequently used to describe actors.

Vi muitos filmes do Ralph Fiennes, e ele trabalha muito. I’ve seen a lot of Ralph Fiennes’ films, and he is really good.

3. celebridade

This is straight forward–celebrity.

Os vencedores do Big Brother Brasil são celebridades nacionais. The winners of Big Brother Brasil are national celebrities.

4. estrela de cinema

This means movie star.

Ela é estrela de cinema, mas é muito humilde. She’s a movie star, but she’s very down to earth.

5. astro

This means superstar.

Pelé conheceu outros astros de futebol na festa. Pelé met other football superstars at the party.