Marsden B was an unused 250 MW oil-fired power station near the Marsden Point Oil Refinery at Marsden Point, Ruakaka, Northland, New Zealand. Due to rising oil prices, the plant was mothballed in 1978 without ever being commissioned. The Marsden site also includes the Marsden A power station, now a synchronous compensation facility owned and operated by Mighty River Power.
Various schemes have been considered for reviving the plant, spanning a range of fuels and technologies. International sale of the generating equipment was also pursued. A 2004 proposal to refurbish it for coal-fired use drew major environmental protests and created drawn-out legal challenges before this proposal was also eventually abandoned.