'Harry Potter' stars Emma Watson and Rupert Grint have been named Hollywood's Top Earning On-screen Couple.

The pair - who played Hermione Granger and Ron Weasley in the wizard franchise - topped the list compiled by Forbes after banking $4.2 billion between them at the global box office in four movies in the series in the last five years.

'Twilight' actors Robert Pattinson and Kristen Stewart - who are dating each other in real life - came second after they picked up $2.5 billion from their portrayals of vampire Edward Cullen and human Bella Swan respectively in the saga.

Shia LaBeouf and Megan Fox earned $1.5 billion after they starred as onscreen lovers Sam Witwicky and Mikaela Banes in 'Transformers' and 'Transformers: Revenge of the Fallen', which narrowly beat the actor's onscreen romance with Rosie Huntington-Whiteley in 'Transformers: Dark of the Moon', which pulled in $1.1 billion.

Robert Downey Jr. and Gwyneth Paltrow's portrayals of Tony Stark and Pepper Potts in the 'Iron Man' films saw them claim fourth with $1.2 billion.

Among the other stars who made up the list were Johnny Depp and Penelope Cruz, who earned $1 billion for 'Pirates of the Caribbean: On Stranger Tides', ahead of Orlando Bloom and Keira Knightley's $963 million for their romance in the first three movies of the series.

Forbes list of Hollywood's Top Earning On-Screen Couples:

1. Emma Watson and Rupert Grint, $4.2 billion, 'Harry Potter'

2. Robert Pattinson and Kristen Stewart, $ 2.5 billion, 'Twilight'

3. Shia LaBeouf and Megan Fox, $1.5 billion, 'Transformers'

4. Robert Downey Jr. and Gwyneth Paltrow, $1.2 billion, 'Iron Man'

5. Shia LaBeouf and Rosie Huntington-Whiteley, 'Transformers: Dark of the Moon'

6. Johnny Depp and Penelope Cruz $1 billion, 'Pirates of the Caribbean'

7. Orlando Bloom and Keira Knightley $963 million, 'Pirates of the Caribbean'

8. Tobey Maguire and Kirsten Dunst, $890 million, 'Spider-Man'

9. Leonardo DiCaprio and Marion Cotillard, $825 million, 'Inception'

10. Sarah Jessica Parker and Chris Noth, $703 million, 'Sex in the City'