Last billing is in fact one of most respected credit positions on the billing block, along with top billing, and is reserved for a high value, usually big name actor either as a guest role in a tv appearance or non-lead role in a movie.
The actor is given final credit by being listed last on the billing block and having a with or and prefix to emphasise their name.
As legend has it, the idea behind Last Billing was conceptualised by Douglas Fairbanks Jr in 1937 during his portrayal of Rupert of Hentzau in The Prisoner of Zenda. He claims in his autobiography that he was unhappy with the billing order so instead of fighting for a position at the top of the billing block he requested to be billed right at the end with an and prefix attached to his name and sure enough he was.