Seth Costello is a fictional character from the British television soap opera Hollyoaks, played by Miles Higson.

He also became involved in the storyline where his father Carl Costello (Paul Opacic) began an affair with Mercedes McQueen (Jennifer Metcalfe).

On 12 April 2010, media entertainment website Digital Spy reported that a new family, the Costello's, would be introduced to Hollyoaks as part of the soap's ongoing rejuvenation.

[1] Newcomer Miles Higson was cast in the role of Seth Costello, the youngest son of ex-model Heidi (Kim Tiddy) and former footballer Carl Costello (Paul Opacic), the brother of Riley (Rob Norbury) and the twin brother of Jasmine (Victoria Atkin).

[3] Of the castings, Hollyoaks series producer Paul Marquess stated: "We can't wait for this huge new boost of energy exploding on screen.

[6] Describing Seth's personality compared to his own in an interview with the official Hollyoaks website, Higson commented: "We're probably very similar.

"[7] In December 2011, it was announced that Higson had finished filming with Hollyoaks and that Seth's final scenes will air at the end of that year.

Seth was revealed to be working with his grandfather Silas Blissett (Jeff Rawle) and girlfriend Theresa McQueen (Jorgie Porter) to blackmail her family into giving them money.

[9] After the conclusion of the storyline which saw Theresa working with her family to get the money back, Seth left in scenes aired in February 2021.

Seth and Riley go to a cage fighting event after being invited by their half-sister Jem's (Helen Russell-Clark) ex-boyfriend Liam McAllister (Chris Overton) who plans to exact revenge on Carl for ending his football career.

Seth begins dating Fern (Amy Gavin) who tells him that Jasmine has gender identity disorder.

He soon rents the pub to Darren Osborne (Ashley Taylor Dawson) and on New Year's Eve, he and Seth leave the village.

Holy Soap describe Seth's most memorable moment as: "Having to clean the pub when Jasmine infiltrated The Loft and took a snap of Sasha, the object of his affections.

"[4] A poll ran on the official Hollyoaks website asked viewers which member of the Costello family was their favourite.

[12] Daniel Kilkelly from Digital Spy wrote that Seth was initially "mild-mannered" and "the quiet man of the [Costello] family", but added that he still was involved in "his fair share of Hollyoaks drama".