In the movie Iron Man, why does Iron Man name his suits as "Mark 1, Mark 2, Mark 3" and so on. How did he came up with that naming pattern?
"Mark" used in this way isn't a name; it's a synonym for "model" or "version". According to Wiktionary, the relevant definition is
A particular design or make of an item (now usually with following numeral). [from 15th c.]
A famous usage of this nomenclature was in the naming of the Colossus Mark I and Mark II computers, used in code-breaking during World War II.
Mark means model or version. It was used for the arsenal of British tanks, the first one being mark 1.