The Wolves vice-president and ex-England cricketer died at the age of 77.
A club statement said she died yesterday morning after a short battle with cancer.
Tributes immediately poured in for Baroness Heyhoe Flint – a lifelong Wolves fan, club vice-president, ex-England cricket captain and proud Wulfrunian.
The flags at Molineux are flying at half mast, while Wolves players will wear black armbands in Saturday's game at Norwich. The England cricket team also boasted black armbands following the news.
Her son, Ben Heyhoe Flint, said last night: "We're deeply saddened and yet we're filled with immense pride as we now look back on her achievements in government, cricket, football, charity and community on which she had such a profound influence. She tackled it all at full speed, showing how grace, a cheeky sense of humour – and tenacity – can break glass ceilings. We hope that we all can continue the legacy that she leaves behind."
Fellow Vice President Robert Plant said: "This is sad news indeed as Rachael was a unique and wonderful lady – straight talking and no messing with bundles of energy, sensitivity and great humour. She loved the city, the people and, of course, the football.
"She was a great ambassador to all three."
She was a pioneer for women's cricket and captained England to victory in the 1973 World Cup in a career spanning two decades.
She was also a successful journalist – serving as sports editor of the Wolverhampton Chronicle in the 1960s – and award-winning after dinner speaker, while she later headed up Wolves' work in the local community.
Her long friendship with Sir Jack Hayward was sparked in 1970, when she asked him to sponsor the England ladies cricket team. After he took over the club in 1990 she was appointed to the club's PR department.
From 1997 to 2003, she served as a director at his request, later becoming a vice-president. She was granted the Freedom of Wolverhampton in 2011. Steve Bull said last night: "She was Wolves through and through and guided Sir Jack into the club. She was bubbly, on her toes all the time. She will be sadly missed. She was like my right arm at the club."
Wolves managing director Laurie Dalrymple said: "She was a wonderful lady who meant so much to so many people in Wolverhampton, and also much further afield. Her contribution to sport, the local community, and politics, cannot be measured, and neither can her seemingly never-ending kindness and generosity of spirit. Her loss leaves a huge gap which is impossible to fill."
City Mayor Barry Findlay said: "Rachael was a fantastic ambassador for our city. She will be sadly missed."
Broadcaster Jacqui Oatley said: "Heart-broken to hear that Rachael has passed away. Our lifelong family friend, an inspiration to so many, a truly special lady."
Piers Morgan said: "She was a pioneer, a great cricketer and a delightful lady."
A book of condolence is being opened at Molineux.