What is the relationship between the following names that often go together is some combination?
I've encountered many men, young and old, with the following first and middle name combinations: Aryeh Leib, Yehudah Leib, and Yehudah Aryeh; and I know one person whose name is Ari but who goes by "Leibel". I also know of some Holocaust survivors whose "English" names (after emigrating to the U.S./Canada) were Leo and Leon, but whose "Hebrew" (and/or Yiddish) names were some combination of the above.
The first two and the last two are easy, as they are actually related: Ari and Aryeh are variants and both mean "Lion"; Leib and Leibel are the same name with just a diminutive suffix added to the former to create the latter.
I can see the connection between Ari and Aryeh to Yehudah, since the sign for the tribe of Yehudah (Judah) is the lion, based on the verse (Genesis 49:9):
"גּוּר אַרְיֵה יְהוּדָה, מִטֶּרֶף בְּנִי עָלִיתָ; כָּרַע רָבַץ כְּאַרְיֵה וּכְלָבִיא, מִי יְקִימֶנּוּ".
But where do Leib and Leibel come from?
Are they derived from Leo?
UPDATE: I can't believe I missed this prominent example (and nobody else raised it): http://en.wikipedia.org/wiki/Yehudah_Aryeh_Leib_Alter