John Charles Haas (May 22, 1918 – April 2, 2011) was an American businessman and philanthropist, at one time considered the second richest man in Philadelphia.

Originally a leather-tanning business, the company expanded into the United States, opening a branch in Philadelphia, Pennsylvania, in 1911.

[5] John Haas became vice president in charge of personnel in 1953, a position in which he promoted the advancement of women and minorities.

He credits his wife with the inspiration to use their personal fortune to target the needs of vulnerable and underserved children and families.

[11] Throughout his life Haas was active with many charitable organizations, including the United Way of Southeastern Pennsylvania, the Boys and Girls Clubs of Philadelphia, the Natural Lands Trust, and the Opportunities Industrialization Center of America, established by Baptist civil rights leader Leon Sullivan.

In 2009 he and his wife gave a 160-acre hamlet known as Waterloo Mills, in Easttown Township, Chester County, to the Brandywine Conservancy for permanent preservation.

[5] Initiatives supported by the William Penn Foundation have included grants to Fairmount Park in Philadelphia, and the development of the Delaware River waterfront.

[5] As of April 20, 2016, the Haas family donated the 42-acre Stoneleigh estate in Villanova, including its Tudor Revival mansion, to Natural Lands.

In developing the garden, Natural Lands has emphasized native plants and sustainable ecological design.

The decorative rabbits, which are a popular feature of the estate, will remain and, in fact, were refurbished as the original sculpture was rotting after years of outdoor exposure.