The actor, born in Omagh, County Tyrone, gave the money to the Dave Gallaher Park in Ramelton, County Donegal, saying the cks captain should be celebrated in his home town, the Irish Independent reported.
Gallaher and his family emigrated to New Zealand in 1878, where he carved an impressive rugby career.
Gallaher led the 1905 "Originals" on their tour of Britain and France.
He died of wounds at Passchendaele in 1917.
In 2005 the All Blacks, led by captain Tana Umaga visited the Letterkenny Rugby Football Club for the unveiling of a memorial after the club named its ground the Dave Gallaher Memorial Park.
"I would like to congratulate the Dave Gallaher Society on this great initiative. Gallaher should be celebrated in his home town," said Neill.
The actor said he was proud of his Irish roots and has an Irish passport.
Neill was most recently on TV screens playing Cardinal Wolsey in The Tudors.
