Joanna Marion Scanlan (born 27 October 1961) is a British actress and writer. On television, she is known for her roles in The Thick of It (2005–2012), Big School (2013–2014), Puppy Love (2014), No Offence (2015–2018), Requiem (2018), and The Larkins (2021). She was nominated for three BAFTA TV Awards for Getting On (2009–2012), including two for Best Writing.

Scanlan's film appearances include Girl with a Pearl Earring (2003), Notes on a Scandal (2006), The Invisible Woman (2013), and Bridget Jones's Baby (2016). She won the BAFTA Award for Best Actress in a Leading Role for her performance in the 2020 film After Love. She was the first person since 2003 to win the award without being nominated for the corresponding Oscar.