Apologies if this has been done to death previously, but there was a post regarding Danny Walker being thought of as a pivotal signing in ten years time, that started me cogs going.
I cam up with three.

Alex Murphy - Brought the good times to Wilderspool during the Seventies.
Darren Burns - Played a blinder and by being first to the ball and booting in into the Fletch saved us from relegation.
Adrian Morley - First statement signing in the HJS era, and gave us some credibility that we could challenge for honours once more.

Anymore for anymore as Ronnie Lane once said?

And here's me thinking that I was the only one who remembered Ronnie Lane.

Dave Chisnall, in his first spell at the club, would be one of my nominations. Overnight he brought aggression,skill and respect to a Warrington pack that had been bullied for a number of years.

In HJ era

Morley (leadership and awesome first 2 years in terms of performance and biff)
Tony Smith (took us to being serial winners 209-2014)
Clark (the heartbeat of our side)
Charnley (true attacking threat and proof that we can sign top players again)

80's Wilderspool
Mike Greg on his 18th birthday - huge influence on club and side for over a decade and rightly attained legend status.
Brian Johnson / Les Boyd / Andy Greg - all had huge impacts on the side at the time.

Peter Deakin
After nearly going bust in the late 90's , Deakin came on board and changed the whole mentality of the club

We'd've been goosed without him

Slim chance of forgetting who Ronnie Lane was.

No player other than John Woods or Johnaton Davis made such an impact across a season...going from perennial mid table teams to cup finalists or league challengers.

Briers? We still haven't replaced him.

Briers in my era, with Morley a close 2nd, hoping walker can be a major significant signing for us. Early days in his career but with Briers to support and coach him and a player of Clarke to watch and learn from , he could be very exciting to watch over the next 10 years

Morley for me, absolute beast, leader, a huge presence and a massive name at the time. It would be like signing Sam burgess now.

Jonathan Davies was a great signing for us, my absolute favourite whilst growing up. Then I'd probably say Alan langer was a coup for the club as well, a proper legend playing for us.

Does Simon Moran count?

Bobby Fulton. Short spell but massive impact in a mediocre side. Warrington born too.

Yes we couldn't buy a win till he guested. But before my time.