She guest starred on the smash-hit BBC show as the team investigated the murder of Henry Ashby, a reclusive pensioner.
Death In Paradise star Don Gilet was joined by his very famous girlfriend in the latest episode - but did you reocgnise her?
The acclaimed actress guest starred on the smash-hit BBC show as the team investigated the murder of Henry Ashby, a reclusive pensioner.
Among the suspects was Fleur Edwards, an artist living next door to Henry, who had moved to Saint Marie for fresh inspiration.
Fleur was played by Happy Valley and Downton Abbey actress Siobhan Finnernan, who debuted a new look for the role.
In real life, Siobhan and former EastEnders and Holby City actor Don have been together since 2018.
The pair began dating after working together on 2017 ITV six-part crime drama The Loch.
The latest episode of Death In Paradise featured an appearance from Don Gilet's real-life partner - but did you recognise her?
Siobhan Finneran guest starred as artist Fleur Edwards, one of the suspects in the latest investigation
The actress' partner Don (pictured) plays Death In Paradise's current lead character, DI Mervin Wilson
Siobhan, 59, played DCI Lauren Quigley while boyfriend Don, 59, starred as Blake Albrighton.
Meanwhile, Death In Paradise viewers enjoyed watching the pair's on-screen interactions.
One wrote on X: 'These spiky exchanges are all the funnier when you know that Siobhan and Don are real life partners #DeathInParadise.'
Fans will recognise Siobhan for playing Janice Garvey on Benidorm, from 2007 until 2015.
From 2010 to 2012, she portrayed servant Sarah O'Brien in Downton Abbey, spanning the first three seasons.
Siobhan later played recovering addict Clare Cartwright in Happy Valley throughout the show's run.
Meanwhile, Don is perhaps best known as serial killer Lucas Johnson in EastEnders, appearing on and off from 2008 to 2024.
He also portrayed Holby City's charismatic and charming Jesse Law between 2014 and 2016.
Elsewhere, Death In Paradise fans were left perplexed by a plot hole at the start of the newest episode
Before the investigation, the team posed in a photoshoot for an initiative intended to bolster public confidence in the police department.
Commissioner Selwyn Patterson (Don Warrington) was unimpressed with DI Mervin Wilson's absence - and demanded to know his whereabouts.
Addressing this, DS Naomi Thomas explained: 'We did try, sir.
Away from the screens, Don and Siobhan have been in a romantic relationship in real life since 2018
They got together after co-starring in 2017 ITV limited crime drama The Loch, where they played a police officer and forensic psychologist respectively
It came as viewers spotted a plot hole towards the beginning of the episode - involving this photoshoot
'He said he's only here short term so didn't think it was his place. Also, apparently, football is on.'
To which the Commissioner fired back: 'And presumably, the crime rate drops every time his team plays?'
Viewers were also left confused, as one wrote on X: 'Mervin says he's here short term when he's been here a year already.'
Another commented: 'Mervin is still only there short term? Huh?'
While a third echoed: 'That's news to me!'
Mervin debuted in the 2024 Christmas special as the replacement for Ralf Little's character, DI Neville Parker.
Subsequently, he carried on as the show's lead character into series 14, which aired in 2025.
Having remained for series 15 - and given the show has made reference to 2026, it would appear the detective has been on Saint Marie for some time now.
Mervin ultimately made it up to his colleagues by the end of the episode, as he joined them for the photo.
Death In Paradise airs on BBC One and is available to stream on iPlayer.