Gwyneth Paltrow shared a farewell message with her Marvel Cinematic Universe co-star Robert Downey Jr.

Gwyneth Paltrow and Robert Downey Jr (c) Instagram

Gwyneth Paltrow and Robert Downey Jr (c) Instagram

The 46-year-old actress - who portrayed Pepper Potts in 'Iron Man' and 'The Avengers' films - recently revealed that she would be giving up her role as the romantic interest of Robert's Tony Stark and that 'Avengers: Endgame' will likely be her final MCU movie.

The 'Shakespeare in Love' star took to Instagram to share a goodbye with the 53-year-old actor and shared a selfie of the pair insisting she would always be "this guy's Pepper".

She captioned the image: "You KNOW I will be this guy's pepper anytime he needs me (sic)" also using the hashtag #pepperonyforever.

Gwyneth previously admitted that she wants to quit the series because she thinks she is a "bit old to be in a suit" now she is in her mid-40s.

She previously confessed: "I mean, I'm a bit old to be in a suit and all that at this point.

"I feel very lucky that I did it, because I actually got talked into it. I was friends with ['Iron Man' director] Jon Favreau. It was such a wonderful experience making the first 'Iron Man' and then to watch how important it has become to the fans."

Although Gwyneth is taking a step back from the MCU she left open the possibility that she'll make a cameo or appear in flashbacks in future Marvel films.

She said: "I feel honoured to be a part of something that people are so passionate about.

"Of course, if they said, 'Can you come back for a day?' I will always be there if they need me."