How are Zack and Sharon related in EastEnders? He only arrived in Walford in 2021 — the tie itself is decades older

Zack and Sharon are half-siblings. They share a father — Gavin Sullivan, played by Paul Nicholas — but not a mother. Sharon's was Carol Hanley; Zack's has never appeared. Neither of them knew the other existed until Gavin died offscreen and they both showed up to see him off.

How the reveal played out

Gavin's sister Sally rings Kathy Beale, his ex-wife, to say he's dead. Kathy and Sharon go to the wake, where a stranger raises a scathing toast to the deceased. Sharon, who loathed Gavin, is delighted to find someone who agrees with her — and while Gavin's cousins chase the stranger off, she quietly drops her father's urn in a bin outside. Only then does Zack, hiding in her car, explain how he knew the man.

Farrar's brief was never to play the sensible new relative. Executive producer Jon Sen, announcing the casting in January 2021, called him a "charming rogue".

Why the tie is older than Zack

Sharon has been in EastEnders since the first episode on 19 February 1985, and her adoption by Den and Angie Watts was written into the show from the start. Gavin only arrived thirty years later — Paul Nicholas played him from 21 August 2015 to 8 July 2016, retrofitted as her biological father. Zack came six years after that. The bloodline was there long before either actor was cast.

Here's who that makes him related to:

• Sharon Watts — half-sister, and briefly his landlady.
• Kathy Beale — Gavin's ex-wife, so technically Zack's stepmother.
• Dennis Rickman Jr and Albie Watts — Sharon's sons, so his nephews.
• Barney Mitchell — Zack's own son, revealed in 2025 after an affair with Nicola Mitchell sixteen years earlier.
• Peach and Dolly Dean-Hudson — his daughters with Whitney Dean.

Are they close?

They were, quickly. Zack moved in with Sharon and Albie, and later took on legal responsibility for Albie — though the arrangement was, in the show's own framing, not remotely legal. The two have spent five years in and out of each other's storylines.

There's one complication worth flagging. Vicki Fowler is Den Watts's daughter, which makes her Sharon's adoptive half-sister. Zack is Sharon's biological half-brother. In 2026 Zack and Vicki kissed — and Kathy walked in on them. No shared blood between the two of them, but the family tree does the rest of the work.

For the record: Gavin left a safety deposit box to Sharon and the key to Zack, forcing the pair to open it together. Inside was nothing worth having.