Williams celebrates ten years with Neath and the Ospreys with a pre-season friendly against European rivals Leicester at the Liberty Stadium on Saturday.
And coach Holley, who has worked closely with Williams at the Ospreys for the last five years, believes the wing deserves his moment of glory.
Holley said: “I don’t think enough has been said about Shane. We are very quick to herald the legends of the past, but in all honesty I don’t think players become true greats in people’s eyes until they stop playing.
“His record of being the greatest try scorer in the game for Wales speaks for itself. Ask any young supporter and they will say their favourite player is Shane Williams.
“That’s a tribute to Shane as a person as well as the way he entertains and approaches the game. Everyone who plays with him is delighted to do so and anyone who plays against him thinks he’s a nightmare.”
Holley has taken over the reigns at the Ospreys alongside forwards coach John Humphreys following the departure of Lyn Jones at the end of last season and is eying his first game in charge ahead of the new Magners League campaign.
He said: “This game is part of our pre-season programme. We will field a strong team against what we expect to be a strong Leicester side.
“It’s also a chance to sample the new experimental law variations, and the fact that we are playing the Tigers later this season in the Heineken Cup is sure to add some extra interest.”
Asked whether Saturday’s game (kick-off 15:00) will add ammunition to the burgeoning competition with the English giants, Holley replied: “It’s a bit early to be scouting against one another but we’re already developing an interesting and healthy rivalry with Leicester after games in the Heineken Cup and EDF finals of past years”.
Ospreys squad:
Backs: Lee Byrne, Gareth Owen, Kristian Phillips, Nikki Walker, Shane Williams, Leigh Bevan, David Bishop, Andrew Bishop, Sonny Parker, Tommy Bowe, Ashley Beck, Daniel Biggar, James Hook, Rhys Webb, Rhodri Wells
Forwards: Paul James, Ed Shervington, Cai Griffiths, Duncan Jones, Marc Breeze, Craig Mitchell, Alun-wyn Jones, Ian Gough, Ian Evans, Andrew Lloyd, Jonathan Thomas, Marty Holah, Tom Smith, Steve Tandy, Ryan Jones, Filo Tiatia