Rose Porteous (born Rosario Magdalena Teresita Lacson on 26 October 1948), is a Filipino-born Australian socialite, best known for her marriage to Western Australia iron ore mining magnate Lang Hancock, and the protracted legal battle with his daughter, Gina Rinehart, over the circumstances that led to his death, and the distribution of his estate. The action, commenced by Rinehart in 1992, was eventually settled in 2003 following a coronial inquiry that determined Hancock died of natural causes. Porteous, who lives in Perth and Melbourne, is often referred to by the media as a socialite.

Born in Bacolod, Negros Occidental, Philippines, Porteous is the daughter of Nicolas Lacson and Amparo Lacson. Her grandfather, Gen. Aniceto Lacson, was a distinguished sugar baron who was also prominent military figure in Negros Occidental during the Philippine Revolution while her uncle, Arsenio Lacson, was the first elected mayor of Manila. Her brother, Salvador L. Lacson, is the chairman of Lacson and Lacson Insurance Brokers Inc., a leading firm since 1973.

After spending time in Hong Kong, Spain, Singapore and Malaysia, Porteous arrived in Australia in 1983 on a three-month working visa. Porteous began working as a maid for the newly widowed Hancock.

Hancock and Porteous became involved over the course of Porteous' employment and they were wed on 6 July 1985, in Sydney. Porteous, who was thirty-nine years younger than her husband, was often accused of gold digging because of their age disparity. As Porteous later stated: "I have been accused of sleeping with every man in Australia ... I would have been a very busy woman." Gina Rinehart, who stood to inherit his entire estate, did not attend the wedding.

Although the marriage would later prove tumultuous, early on Hancock was clearly infatuated with his young wife. He gave her money and investments in real estate in the Sydney area. Porteous, in turn, helped Hancock to look and act like a much younger man, belying his eight decades. As The Age put it, "Rose made Lang feel younger, sprucing up his wardrobe, dying his hair and getting rid of his cane". Together they built the "Prix d'Amour", a lavish 16-block mansion overlooking the Swan River. The mansion, which was modelled after Tara, the plantation mansion in the movie Gone with the Wind, was the setting for many large parties at which Hancock and Porteous would "dance into the night".

As the marriage wore on, however, the relationship between Hancock and Porteous began to break down. Rumours surfaced of her having disputes with servants and others close to Hancock, especially Rinehart, and as Hancock's health worsened, so did his relationship with Porteous. Rinehart would later claim that Hancock's bride had paid little attention to his worsening health, but had instead "screeched at him for money". Although there were many quarrels, Hancock and Porteous remained married until his death in 1992.

Porteous rose to prominence in the 1990s as the central figure in a series of lawsuits launched by her step-daughter, Gina Rinehart. Rinehart is the daughter of Lang Hancock and Hope Margaret Nicholas, Hancock's second wife. On 25 June 1992, less than three months after Hancock's death, Porteous married for the fourth time, to Hancock's long-time friend William Porteous. Rinehart was indignant at the haste with which her stepmother had remarried.

Central to Rinehart's lawsuits were the accusations that Porteous married Hancock only for his fortune and alleged that her stepmother's actions had contributed to her father's death. According to his daughter, the death was "unexpected" and came "despite strong will to live". An autopsy showed that he had died of arteriosclerotic heart disease and police investigation revealed no evidence to contradict that. However, Hancock's daughter insisted that her stepmother had unnaturally hastened his death. Two successive state coroners refused to allow an inquest, but one was eventually granted in 1999 under the direction of WA Attorney-General, Peter Foss.