Architect Rick Mather, whose masterplan for the redevelopment of the arts complex on the South Bank was published in 2000, has died at the age of 75.
According to a notice published on Monday on the website of Rick Mather Architects, the American-born architect died on Saturday "after a short illness".
He had been associated with the South Bank for a decade and a half.
"We were very saddened to hear about the recent death of Rick Mather," said a Southbank Centre spokeswoman.
"Rick's masterplan for Southbank Centre, created in 2000, has played a major role in making the site the vibrant and successful destination it is today.
Alan Bishop, chief executive of Southbank Centre, said: "Rick was both passionate about and proud of what had been achieved at Southbank Centre, and it's very sad that he won't witness the fruits of his labour as the Festival Wing project develops.
"He will be hugely missed and our thoughts are with his family, friends and colleagues at this time."
Last month Mather welcomed the plans prepared by Feilden Clegg Bradley Studios for the next phase of the redevelopment of the South Bank arts campus.
He said: "It is most encouraging to see momentum developing for the Festival Wing proposals at Southbank Centre.
"FCBS has successfully engaged with the challenges presented by the unique and complex 1960s buildings and landscape.
"They have refined a set of proposals which are based on our agreed urban design principles.
"The design demonstrates a deep understanding of the current and future needs of Southbank Centre."