Willow Harris (also Ranger) is a fictional character from the Australian television soap opera Home and Away, played by Sarah Roberts. The character made her first screen appearance on 14 November 2017. Roberts had auditioned for the roles of both Kat Chapman and Scarlett Snow prior to playing Willow. She auditioned successfully and attended screen testing with James Stewart who play's Willow's love interest Justin Morgan. Willow was originally going to be named Amber. She is characterised as a tough female who was raised in a broken home and has subsequently learned to look after herself. Roberts has said that she admires the character's strong personality. Willow is introduced into the show wearing leather, chains and riding a motorbike. This added to her image as a powerful female character.

Writers quickly paired her with Justin and their relationship is marred by a feud with gang member Boyd Easton (Steve Le Marquand). His family kidnap Justin's daughter Ava Gilbert (Grace Thomas), which ends the relationship. Producers introduced Willow's ex-boyfriend Dean Thompson (Patrick O'Connor) and the characters resume their relationship. A gambling addiction story was written for Willow and she ends up stealing, loaning money, scamming people and squatting. Roberts found the gambling story challenging and carried out extensive research to accurately portray the issue. The character has been well received by critics of the genre who analysed her strong personality and dramatic introduction into the series. In March 2021, Roberts confirmed that she had left Home and Away and her final appearance aired on 14 April 2021.

Prior to securing the role of Willow, actress Sarah Roberts auditioned for both Kat Chapman and Scarlett Snow. Roberts recorded her first audition for the part while residing in Los Angeles. She flew up from Melbourne to Sydney for the on-set audition and had a chemistry reading with James Stewart, who plays Justin Morgan. Roberts did not think she had won the part, as it took a while for the producers to contact her. The character was originally supposed to be named Amber but this was later changed to Willow. Roberts remembered her first day playing Willow as "awesome", recalling dressing in leather, chains and transforming into character. Willow made her first on screen appearance during the episode broadcast on 14 November 2017.

Filled with energy and fun, the attractive, fit and dynamic Willow Harris is a delight – but cross her and it's like having a firecracker go off in your face. Raised a single child in a broken home to a rough 'n' tumble dad, she learnt to look out for number one early.

— An excerpt taken from The official Home and Away website.

Willow is characterised as "a tough, dynamic and powerful" female and is surrounded by mostly male characters. Roberts made sure she was strong on set to "do justice to her character" in the male dominated scenes. She was raised by her father, a single parent, which made Willow learn how to look after herself early in life. Roberts has described Willow as a "strong female character", who is also independent, loyal and fierce. The actress said Willow would bring "mischief and a bit of trouble" to Summer Bay. Willow's introduction into Home and Away showcased her characteristion. Roberts said that Willow proves herself to be "a tough cookie – she's a total firecracker", as she rides into Summer Bay on a motorbike. She immediately makes herself known to Justin and accuses him of stealing $15,000. Roberts said that Willow validates her tough persona in the scenes where she attacks Justin, ties him up and locks him in his garage overnight. Roberts told Tamara Cullen from TV Week that Willow "rode into town with a lot of power, she's definitely going to cause some mischief!"

Roberts told a journalist from New Idea that Willow was "definitely a bad girl. But for all the right reasons. She has taken wrong turns and made decisions that some people would consider 'bad', but only to help the people that she loves." In another interview the actress described Willow as "very sassy and fun. She's got attitude. I think she's a woman who knows what she wants and won't stop until she gets it, but is also fiercely loyal and will do anything for the people she loves." Roberts liked her character's "really strong" and "feisty" side and believed the character would stop at nothing to get what she wants. Willow had a difficult life and upbringing, as a result she "put a guard up" not allowing others to emotionally connect with her. Willow has a "tougher" wardrobe than that of a traditional feminine one. This helped Roberts to get into character, with her explaining that "I put on her costume and totally feel like her."

Willow was introduced into the show as a new love interest for Justin Morgan. Her first story follows her getting into trouble with Boyd Easton (Steve Le Marquand) because she owes him money. He attacks Willow's father and pushes him down stairs. He then vandalises Justin's garage to serve as a warning to help Willow return the missing money. Justin tries to reason with Boyd and his biker gang but the meeting turns violent, leaving Justin bruised. He reports the incident to the police which gets Boyd arrested. Ash (George Mason) tries warn Justin to stay away from Willow, he fear for her safety and convinces Willow to move into the local caravan park. Claire Crick from Soaplife reported that Justin quickly assumes the role of Willow's "knight in shining armour". She added that despite Willow causing trouble for Justin, he cannot stop thinking about her. Stewart told Sarah Ellis from Inside Soap that "Justin is becoming quite protective of Willow" and his character "is thrilled" when he gets to spend time with her. Roberts and Stewart soon began a relationship off screen. Roberts believed their own romance made playing an on screen couple easy. She told Fiona Byrne from the Herald Sun that "i did not even have to create any chemistry when I was on screen with Jimmy, it was all just there, it was not a job."