He's mostly come off the bench in this tournament, just like four years ago. Only his impact this time has been far more profound.
Williams all but rescued the All Blacks from a tight spot in their opening pool match against Argentina and his cameos against South Africa was hugely influential in the final minutes.
Coach Steve Hansen says that Williams returned to rugby from league a "massively better" player.
Williams has also provided this World Cup with its enduring image: the shot of him comforting devastated Springboks rival Jesse Kriel which went around the world and drew him plaudits for his sportsmanship.
Olympic gold medal in 2016
The Kiwis have their eyes firmly set on claiming gold when rugby sevens debuts at the Rio Olympics next year, and none more so than 30-year-old Williams.
SBW is expected to join the sevens circuit with the New Zealand side and play at least six tournaments in lieu of another season in Super Rugby to adjust to the shortened format.
"Going back in time the best sportsmen ever have been Olympians," Williams said in August of the opportunity before him.
"[Usain] Bolt, [Muhammad] Ali, the list goes on. It's just an amazing opportunity to become one of those."
Once the Olympics and Williams' commitments to the sevens programme wrap up, he's tied to another year with the NZRU, by which stage he'll be 32.
Williams has said previously he's not the type of athlete that wants to keep going until he's 40. But it's also hard to imagine the man who brought one-year contracts into vogue not picking up at least one or two more before he wraps up.
European rugby and his old haunt of Toulon - one of the rare places he never won a title - is sure to be an attractive option, and eccentric owner Mourad Boudjellal is already sniffing about.
Roosters boss Nick Politis will have the inside running should a return to league appeal, while a return to the ring at some point has also been indicated by Williams as well.
Now we trek back through Williams' already impressive list of achievements.
Sonny Bill Williams played a minor role four years ago. Photo / Brett Phibbs
This is the one that comes with the largest grain of salt, as SBW's contribution to the Kiwi cause was somewhat of a footnote.
An injury to flyer Corey Jane saw Williams nab some tries and a few surprise starts on the wing during the pool stages, but five token minutes at the end of a nailbiting final against France left no doubt as to where he stood in the All Blacks' three-quarter pecking order.
The snubbing from coach Graham Henry stuck with Williams given he'd been playing the house down with the Crusaders, and two years later he told The Australian's Greg Bearup: "I didn't want to be picked for my name, but I was in form. I was playing some pretty good rugby, hey, and I felt I had been lied to."
Three Bledisloe Cups in 2011, 2012 and 2015
SBW's last moments of his first stint in rugby union saw him laying on a try for Israel Dagg with one of his trademark offloads at Eden Park.
It was the only try in a 22-0 victory for the All Blacks - the first time they'd held the Wallabies scoreless in 50 years - and one that secured Williams' second Bledisloe Cup in as many years.
A year earlier he'd come off the bench in a limited role as the Kiwis spanked Australia 30-14 at the same ground. So take that as you will.
Likewise the claims to the 2015 triumph, given he started in Sydney when the Wallabies sprung a 27-19 upset, and was left out of the side when the All Blacks returned serve to claim the cup again with a 41-13 shellacking.
Two NRL Premierships in 2004 and 2013
The first title was secured with a brilliant Bulldogs outfit in 2004 that had a point to prove to the world after salary cap and sex scandals had dogged them in previous years.
Williams came off the bench as the best young player in the game - hell, the best young player the game had seen in donkey's years - and had a profound impact in an enthralling 16-13 triumph over the Roosters.
Nine years later and out the other side of the most despised exit in rugby league history, Williams returned with the Roosters and all eyes were on him.
His 2013 season picked up right where he'd left off with the Bulldogs in 2008, as one of the most devastating individuals in the league.
The performance he turned out in the Roosters' 26-18 grand final defeat of Manly was worthy of the Clive Churchill Medal according to plenty of astute judges.
SBW shows off the NRL title to his adoring fans. Photo / Getty
World Club Challenge in 2014
Having starred all 2013 for the Chooks, Williams was front and centre when their 2014 campaign kicked off with a comprehensive 36-14 defeat of English Super League champions Wigan.
Super Rugby Title in 2012
No doubt about this one, with Williams instrumental in the Chiefs' maiden Super Rugby championship, claiming the club's player of the year award and making more offloads than any other player in the competition.
It was SBW setting up the first and second tries of the night in the Chiefs' 37-6 demolition of the Sharks in the decider, before running in for the last try, after which he simply kept running straight into the crowd to kick off the celebrations.
Heavyweight boxing titles in 2011 and 2013
Again, make of these what you will considering the two belts Williams has won in the ring have their own stories to tell.
Both his WBA International Heavyweight title and the New Zealand Professional Boxing Association Heavyweight title were subsequently stripped from Williams when he failed to respond to challenges within the required six months, mostly due to his footballing commitments.
How hard he had to work to earn them in the first place is also up for conjecture, but there's no denying it's his name in the record books.
Sonny Bill Williams celebrates with his WBA international heavyweight title. Photo / Getty
In 2012, he claimed the NZBPA's Heavyweight title with a first round TKO of Clarence Tillman III, a replacement fighter who was called into the ring when original opponent Richard Tutaki's impending criminal charges saw him dropped from the card.
His WBA Heavyweight title was also marred in controversy over claims his opponent Francois Botha was not informed the fight would be reduced from 12 to 10 rounds shortly before the first bell.
Williams won by a unanimous points decision, but found himself almost floored by a heavy Botha right in the last round.
