Marvel's Paltrow, Evans and Brolin join to help Robert Downey Jr celebrate 55th birthday on lockdown

Robert Downey Jr's 55th birthday was spent on lockdown in Los Angeles, but it was still a star-studded affair.

His Avengers co-stars including Gwyneth Paltrow, Chris Evans and Josh Brolin were among those sending celebratory messages.

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In a video post via Instagram, Brolin – the late Thanos from the MCU – called RDJ a 'sweet man', a 'stud' and 'gift to humankind'.

Chris Evans – Captain America – added: “Happy birthday to one of my absolute favorites! Love you 3000.”

Gwyneth Paltrow - Pepper Potts - also chimed in: “I must wish my dear, dear @robertdowneyjr a happy birthday. Here he is, making a toast at our wedding, during which his humor elicited my usual look of pure joy/shock whenever he is near.

“He is my brother, friend and supporter. A mega genius, and the weirdest comedy writer of all time. I know all of our @marvel family join me in wishing him a very happy day. Do you love Robert? Let him hear you if you do. We love you RDJ.”

Mark ‘The Hulk’ Ruffalo added:

Downey Jr posted his own inspirational message on his special day too, quoting the late Maya Angelou.

“If u don’t like something, change it. If you can’t change it, change your attitude…’ #mayaangelou #happybirthday #Poet#Activist 1928-2014 It’s an honor to share a birthday with this great #woman,” he wrote on Instagram.

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He also noted 'a necessity to express my #gratitude to the following — #Healthcare workers, Personal care and home health aides, First responders, Anyone in an active service job, As well as law enforcement, the National Guard, all Armed Services, etc… Anyone braving exposure in the #service of others— Proudly, RDJ.”