Mythology is about Greek mythology.

Thor is a renowned character in Scandinavia mythology.

M. A. Dwight has written:

'Grecian and Roman mythology for schools' -- subject(s): Classical Mythology

'Grecian and Roman mythology' -- subject(s): Greek Mythology, Roman Mythology

'Grecian and Roman mythology' -- subject(s): Classical Mythology, Greek Mythology, Roman Mythology

E. M. Berens has written:

'A hand-book of mythology' -- subject(s): Classical Mythology, Mythology, Classical

'A hand-book of mythology' -- subject(s): Classical Mythology, Mythology, Classical

'A handbook of mythology' -- subject(s): Classical Mythology

'A hand-book of mythology' -- subject(s): Accessible book, Classical Mythology

Yes and no. Irish Mythology is a subset of Celtic Mythology. Celtic Mythology also includes Scotish, Welsh, and British Mythologies. But Irish Mythology is also included.