Who Is Siobhán McSweeney? From Derry Girls’ Sister Michael to The Traitors Ireland

Siobhán McSweeney is welcoming UK audiences into Slane Castle as the second series of The Traitors Ireland continues on BBC iPlayer.

With her extravagant costumes, sharp humour and commanding Round Table appearances, the fabulous Irish actress has made the role distinctly her own.

But her career extends far beyond the castle. From studying biological science to winning a BAFTA for Derry Girls, Siobhán has built an impressive career across television, film, theatre and presenting.

Where is Siobhán McSweeney from?

Siobhán grew up in Aherla, County Cork, Ireland, surrounded by a family with strong connections to Irish culture, literature and education.

Her father worked in customs and excise and was an Irish speaker, while her grandfather was a poet. As a child, she enjoyed reading and attended speech and drama classes, developing an early love of performing.

She studied biological science at University College Cork, graduating in 2001. During her university years, she became involved with the drama society and performed at Cork’s Granary Theatre.

Her enthusiasm for acting eventually took her to London, where she trained at the Central School of Speech and Drama before establishing herself as a professional performer.

How did Siobhán McSweeney become famous?

Siobhán became internationally recognised in 2018 when she began playing Sister Michael, the wonderfully sarcastic headmistress of Our Lady Immaculate College in Channel 4’s Derry Girls.

Created by Lisa McGee, the comedy followed a group of teenagers growing up in Northern Ireland during the 1990s, with Sister Michael providing some of the programme’s most memorable moments.

Her wonderfully dry observations, disapproving expressions and quick wit made the character a favourite throughout the show’s three series.

Derry Girls became an international success, introducing Siobhán to audiences around the world and establishing Sister Michael as one of the comedy’s standout characters.

What other television shows and films has she appeared in?

Siobhán’s television credits include The Fall, No Offence, Collateral, Holding, Death in Paradise and Redemption.

She played Mary, the mother of Jen, in Disney+’s superhero comedy Extraordinary, appearing across both series. More recently, she portrayed celebrity chef Della Fry in the BBC comedy Amandaland.

Her film appearances include The Wind That Shakes the Barley, Alice Through the Looking Glass, Nowhere Special and The Electrical Life of Louis Wain.

Theatre has also played an important role in her career, with performances at the National Theatre, Royal Shakespeare Company and Dublin’s Abbey Theatre.

Her stage work includes As You Like It, Dancing at Lughnasa and The Alchemist, demonstrating her versatility across comedy, drama and classical theatre.

What awards has Siobhán McSweeney won?

One of Siobhán’s biggest career achievements came in May 2023 when she won the BAFTA Television Award for Female Performance in a Comedy Programme for Derry Girls.

The award celebrated her portrayal of Sister Michael during the comedy’s final series and marked a memorable moment in her television career.

During her acceptance speech, she paid tribute to her late mother and thanked the people of Derry for embracing both her and the programme.

In November 2024, University College Cork honoured her with an Alumni Achievement Award, recognising her contribution to entertainment and the arts.

The university celebrated her journey from biological science graduate to internationally recognised actress and presenter.

How did she become the host of The Traitors Ireland?

Siobhán was announced as the presenter of The Traitors Ireland in December 2024, bringing her theatrical experience and distinctive humour to the Irish adaptation of the international television format.

Filmed at Slane Castle in County Meath, the programme sees contestants compete in missions while attempting to identify the Traitors secretly working against them.

Siobhán has embraced the production’s theatrical possibilities, developing an elaborate castle-owning persona sometimes described as Lady Muck.

Her wardrobe is a particularly memorable feature. For the second series, she drew inspiration from Irish history and mythology, including the legendary pirate Gráinne Mhaol.

Costume designer Sophie Brunkard created a fantastic custom outfit for the programme, with styling by Anne O’Shea and a headpiece by Michelle Kearns.

The programme has now completed two successful Irish series, with a third commissioned for 2027.

What else does Siobhán McSweeney present?

Since 2021, Siobhán has presented Channel 4’s The Great Pottery Throw Down, joining judges Keith Brymer Jones and Rich Miller as amateur potters compete in creative challenges.

She also hosted Siobhán McSweeney’s Great Outdoors, exploring Northern Ireland’s landscapes, history and communities.

Her latest presenting project is Comfort Eating, the popular celebrity podcast previously hosted by Grace Dent.

Siobhán is taking over for its eleventh series, welcoming famous guests to discuss their favourite foods, childhood memories and the stories behind their most comforting meals.

The new series is announced for November 2026, with ten weekly episodes and guests including Asim Chaudhry, Nicola Coughlan, Caitlin Moran and Ed Balls.

Where can you follow Siobhán McSweeney?

Siobhán’s Instagram account, @siobhni, has approximately 245,000 followers and features updates about her television projects, theatre appearances, colourful costumes and causes she supports.

Where can you watch Siobhán McSweeney?

Both series of The Traitors Ireland are listed on BBC iPlayer, with new episodes of series two being released weekly for UK viewers.

Derry Girls and The Great Pottery Throw Down are available through Channel 4 streaming, while Extraordinary can be watched on Disney+ and Amandaland on BBC iPlayer.

Her Comfort Eating podcast offers another opportunity to enjoy Siobhán’s humour and personality away from her scripted television roles and the castle.