Never-ships were bizarre Dalek craft that were, along with the Skaro Degradations, mined from redundant timelines created by the Last Great Time War, the result of untold Time Lord interference.
There were many different looking never-ships; some were vast silver globes bristling with antennae and weaponry, others dart-like ships resembling enormous eyestalks, others blue and gold cylinders rippling with round nodules that seemed alive, and a cannon so large its main shaft was suspended between four huge Dalek saucers, lashed to rigid supports.
These ships were used by the Dalek armada at the Althos system, but were destroyed by the War Doctor when he detonated proximity mines in Althos II, igniting the system. (PROSE: Decoy)