Some of the nominations on this thread are utterly ridiculous.
Tim Sheens - 4 premierships and the greats coach Canberra, Wests Tigers and Penrith have ever had. He is also the best coach either joint venture side had since Warren Ryan. Brought through some of the greatest players in the history of the game.
Chris Anderson - 2 premierships, yes the one marker system was ridiculous and the way he treated Preston Campbell ruined a potentially excellent Sharks side. But his work with the Bulldogs and Melbourne shouldn't be overlooked. Also the fact that every team in the competition uses the flat attack style works in his favour he did actually revolutionize the game.
Matt Elliott - Overachieved with Canberra in 2003 despite what Raiders fans say. Had a good season with Penrith in 2010 again they over achieved. Elliott isn't the worst shout in regards to coaches who continually keep getting jobs. But he isn't the worst coach ever of all time.
Royce Simmons - Another ridiculous suggestion Penrith made the finals in 1997 and 2000. Penrith would have made the finals again in 1999 but had a horror run of injuries, Penrith were top of the table that season with the best defence in the competition then came probably the worst injury crisis the club has ever suffered. He wasn't that bad of a coach 2001 was a terrible season but he did sign Luke Priddis, Martin Lang, Ben Ross and others gave debut's to Luke Lewis and Luke Rooney that season. Which ultimately helped lead Penrith to premiership success in 2003.
Tommy Raudonikis - Tommy get's a lot of mentions for this accolade but the 98 and 99 Wests side were just terrible on paper even if Jack Gibson was coaching them they would of still struggled. He guided the club to a finals berth in 1996 and was unlucky not to do it again in 1997.
Personally despite him winning the Rugby League world cup the worst club coach of all time by an absolute mile was Stephen Kearney. His entire game plan was one out hit up and bomb the Eels were abysmally bad under Kearney.
Alan Jones deserves a mention also he took over quite an old Balmain team but a massively successful one and turned them into a mediocre side which they never recovered from.
Langmack was terrible too but that might be down to Souths and Terry Lamb was awful too.