Alexandrine: in French verse a line of twelve syllables, and, by analogy, in English verse a line of six stresses. Drama poets often used alexandrines before Marlowe and Shakespeare popularized iambic pentameter.( =hexameter, usually iambic)
Hexameter: the hexameter line (6-stress line) is the meter of classical Latin epic; while not imitated in that form for epic verse in English, some instances of the hexameter exist.
Examples: From Pope's "Essay on Criticism":
(line 3) "But of the two less dangerous is the offense"
(line 357) "That, like a wounded snake, drags its slow length along."