Foy was the first actor to play the Netflix series' lead role and starred as Queen Elizabeth II for the first two seasons, portraying her younger years and early romance with Prince Philip (Matt Smith).
Read more: Who's who in The Crown season 5 cast
She was succeeded by Olivia Colman for seasons three and four, and Imelda Staunton has taken over the role for the final two seasons, but Foy makes a return for some flashback scenes in the new episodes.
One emotional fan tweeted: "i just cried the biggest tears #thecrown," as Foy appeared back on screen.
— celia (@kirbiscuits) November 9, 2022
Season five opens with a recreation of an old black and white news report of the Queen's visit to John Brown's yard on Clydeside in 1953, where she launched the then new ship HMS Britannia.
The scenes feature Foy back in her former role for the second time, as she also made a flashback appearance in season four.
Read more: Where was The Crown season 5 filmed?
In her launch speech, Foy as the Queen says: "I am delighted to join you in Clydebank today for the launch of this, the latest royal yacht.
"I hope that this brand new vessel, like your brand new Queen, will prove to be dependable and constant, capable of weathering any storm. I now take great pride in naming this ship Britannia."
here is the full clip of the queen claire foy opening the crown season 5 pic.twitter.com/r2cqgF4uyd
— fay | the crown spoilers (@rachelweiszmilf) November 9, 2022
One fan tweeted: "THE WAY I SCREAMED WHEN CLAIRE SHOWED UP"
Someone else added: "my favourite genre is claire foy coming back for flashback elizabeth scenes"
Another viewer simply wrote: "QUEEN CLAIRE FOY IS BACK"
Many of the show's fans shared that they felt it was at its best during Foy's reign and commented that they were pleased to see her back in the role.
One person tweeted: "claire foy you will always be the crown"
Someone else added: "the crown will always be claire foy’s home"
Another viewer shared: "i love olivia and im sure i will love imelda but claire foy will always be the crown."
The scene cut to the 90s, where the Queen as played by Staunton was being asked by prime minister John Major (Jonny Lee Miller) to find funding for repairs to HMS Britannia that did not come from government money.
Staunton recently said of taking over the role: "I knew it was a very heavy baton that was being passed over, so I had to try and match what had gone before.
“I didn’t want to let the whole thing down. I had to get over the shock of doing it and the fear.”
The Crown season five is streaming now on Netflix.
Watch: The real dramas that didn't make it to the final cut of The Crown