<Li> Catherina "Cath" Smith (Pam Ferris) - Smithy (James Corden) and Rudi's (Sheridan Smith) mother who first appears in the first episode of Series 3 . She is rumoured to have had a lesbian relationship with the headteacher of Gavin (Mathew Horne) and Smithy's primary school . She claims to suffer from narcolepsy, though Pam (Alison Steadman) attributes this to her excessive drinking . She attends single mother support groups and has been known to perform lewd acts on webcam, having once accidentally exposed herself to Nessa (Ruth Jones) thinking she was a man named John . </Li> <Li> Doris "Dor" O'Neill (Margaret John) - Gwen's (Melanie Walters) elderly next door neighbour . She looks like a stereotypical "little old lady", in sharp contrast to her behaviour and blunt, profanity - littered conversational style . Doris regularly dates younger men, even offering herself up to Gavin (Mathew Horne) for "discreet" extramarital relations, and is described by Bryn (Rob Brydon) as "a player". She has a daughter named Moira, whom she loathes and would like to "smother" if she saw her again . Gwen even goes so far as to say "she was a nasty piece of work". It is Doris who spots the unfortunate coincidence of Gavin and Stacey (Joanna Page) sharing the West and Shipman surnames with serial murderers Fred and Rose West and Harold Shipman . </Li> <Li> Ruth "Rudi" Smith (Sheridan Smith) - Smithy's (James Corden) sister, also likes to be called "Smithy" in an attempt to imitate her brother, with whom she often fights . </Li> <Li> Neil Noel Edmund Smith aka Neil, the Baby - The son of Smithy (James Corden) and Nessa (Ruth Jones), named after both Smithy and Nessa's father . His middle names come from Smithy's uncle Edmund and Nessa's friend Noel from Hear'Say . </Li>

Who plays smithys sister in gavin and stacey