Niamh Walsh (born 17 April 1988) is an Irish actress. She is best known for her role as Cara Martinez the in BBC One medical drama Holby City. Walsh also appeared in Casualty and Jekyll and Hyde. She starred in the Sky 1 period drama Jamestown as Verity Rutter née Bridges. Before production, Walsh stated that she "researched a lot for this role. I love all that stuff. Bill [Gallagher] used real people as the basis for some of his characters. And by reading books about the period you learn little things that even if the audience doesn’t see it, it adds to your performance."

In 2021, Walsh appeared alongside Dervla Kirwan, Seána Kerslake and Gemma-Leah Devereux in the RTÉ One thriller drama series Smother, in which she portrayed Jenny, the eldest Ahern sibling. In an article with the Irish Independent, Walsh shared her interest in portraying one of the powerful and independent woman in the series, as stated:

It took long enough, but people are sort of realising that women are just as complicated as men. We contain multitudes. There aren’t just three types of women out there… It’s so comforting to see that we’re sort of just being allowed. We’re being allowed the complexity that men have been allowed for years. We are no longer being jammed into boxes.

On 26 May 2021, Walsh was cast in the Netflix adaptation of DC Comics's The Sandman, portraying the young Ethel Cripps