Wildfire
Wildfire is Ace Rimmer's personal ship. Wildfire is a one-man craft with only a cockpit, and is run by a computer who has a crush on Ace Rimmer. It first appeared in the episode "Dimension Jump", which also introduced Ace Rimmer. Its second appearance was in the episode "Stoke Me a Clipper", where it was slightly redesigned, being small enough to fit inside Starbug's hangar.
Wildfire was created in Ace Rimmer's own dimension by his team on Mimas, including "Spanners" Lister, and is capable of crossing the barrier between alternate dimensions. Ace Rimmer agreed to test-fly it even though it was a one-way ticket as there was no way of returning to his own dimension, but he couldn't resist due to his natural character of daredevil bravado. Ace used it to cross into our dimension where he met the Dwarfers. Afterwards he used it as his own dimension-jumping spaceship, and gained a reputation across many alternate dimensions as a kind of intergalactic space adventurer and dashing hero.
Ace Rimmer "caught the business end of a neutron tank in Dimension 165", after which another version of himself in that dimension took up his persona and continued adventuring through the dimensions with Wildfire. This has since occurred many times since and many alternate counterparts of Ace from various dimensions have piloted Wildfire. When each Ace dies, Wildfire is given to the next one in the counterpart dimension.
Wildfire is never named in the TV series: it's only named in the Red Dwarf novel Backwards, where it was built on Europa rather than Mimas. In that novel (the novels had different stories to the TV series) Wildfire is taken by Lister and Cat after Ace dies so they can escape the sun Starbug is flying towards.