Unsinkable Sam AKA Oscar was a ships cat. He served during the second world war on board three different vessels and survived the sinking of all three! He was picked up by the HMS Cossack, and was the only survivor picked up by that ship. Oscar was on the Bismark. He was floating on a piece of wood debris. The crew of the Cossack named him "Oscar".
The Cossack was torpedoed by a U boat in October 1941, killing 159 members of the crew. Oscar survived.
Oscar and surviving crew were rescued by the HMS Legion. Oscar never joined Legion's crew. He was put ashore with the rest of the survivors at Gibraltar. He was then assigned to the HMS Ark Royal.
The Ark Royal was hit by a torpedo and sank and again Oscar was rescued, this time by HMS Lightening.
Oscar was then assigned to the Governor of Gibraltar's office and from there he was "transferred" back to Belfast, where he sat out the rest of the war.
His portrait is in the National Maritime Museum
Paws On Your Heart has additional information
Oscar died in 1955 but does have a facebook page!