It's Big Overseas.

How names catch on is fascinating. Why Connor and not Conall? Aubrey but not Audley? While I'm sure part of it has to do with namesakes, as well as phonetic trends, there are some name families that aren't really used in the US at all. Their variants can be found in many other languages, but are practically unheard of in English (sometimes just American English).
Weird.

Boys:

• Albin (AHL-bin, German; AHL-been, Scandinavian, Polish, Slovene)
• French form is Aubin
• Ambrose (AM-brohz, English)
• other forms include: Ambroos (Dutch), Ambroise (French), Ambrus (Hungarian), Ambrogio (Italian), Ambrosio (Spanish), Emrys (Welsh)
• Aurélien (oh-rayl-YAWn, French)
• other forms include: Auréle (French), Aurel (German, Romanian, Slovak), Aurél (Hungarian), Aurelio (Spanish, Italian), Aureliusz (Polish)
• Constantine (KON-stan-teen, English)
• other forms include: Constantijn (Dutch), Constantin (French, Romanian), Costache/Costin (Romanian), Costanzo/Costantino (Italian), Konstantinos (Greek), Konstantin (German, Hungarian, Russian, Serbian), Konstanty/Konstantyn (Polish)
• Cyril (SEER-il, SIH-ril, English)
• other forms include: Ciril (Catalan, Slovenian), Cirillo (Italian), Cyrille (French), Kiril (Bulgarian, Macedonian), Kirill (Russian)
• Emil (eh-MEEL, English, EH-meel, German)
• other forms include: Émile/Emilien (French), Emilian (Romanian), Emiliano/Emilio (Italian, Portuguese, Spanish), Emilis (Lithuanian)
• Gaëtan (gah-eh-TAHN, French)
• other forms include: Caetano (Portuguese), Cayetano (Spanish), Gaetano (Italian), Kajetan (Czech, German, Polish, Slovene)
• Gustav (GOOS-tahf, Czech, German, Scandinavian)
• other forms include: Gustave (French), Gustavo (Italian, Portuguese, Spanish), Gustavs (Latvian), Gustaw (Polish), Kustaa (Finnish)
• Ishmael (ISH-mayl, English)
• other forms include: Esmail (Persian), Ismael (French, Scandinavian, Spanish), Ismail (Arabic, Bosnian, Turkish), Ismo (Finnish)
• Joachim (JOH-ah-kim, English; zhoh-ah-KEEM, French; yoh-AH-keem, German, Scandinavian, Polish)
• other forms include: Gioacchino/Gioachino (Italian), Jaakkima (Finnish), Jáchym (Czech), Joakim (Scandinavian, Serbian), Joaquim (Catalan, Portuguese), Joaquín (Spanish), Jochem (Dutch, German), Yakim (Russian)
• Marius (MAHR-ee-us, MEHR-ee-us, English; MAH-ree-oos, French, German, Romanian, Scandinavian)
• other forms include: Marijo (Croatian), Mario (Italian, Spanish), Mário (Portuguese), Marios (Greek), Mariusz (Polish)
• Rayner (RAY-ner, English)
• other forms include: Ragnar (Scandinavian), Rainer/Reiner (German, Scandinavian), Rainerio (Italian, Spanish), Rainier (French), Raniero (Italian), Reinier (Dutch)
• Urban (UR-ban, English; OOR-bahn, German, Polish, Scandinavian, Slovene)
• other forms include: Urbain (French), Orbán (Hungarian), Urbano (Italian, Spanish)
• Valentine (VAL-en-tine, English)
• other forms include: Balendin (Basque, Spanish), Balint (Hungarian), Valentijn (Dutch), Valentin (Bulgarian, Czech, French, German, Romanian, Russian, Scandinavian), Valentino (Italian), Walenty (Polish)

Girls:

• Apollonia (ah-poh-loh-NEE-ah, Greek)
• other forms include: Abelone (Danish), Apolena (Czech, Slovak), Apoliena (Slovak), Apolline (French), Apolonia (Polish), Apolónia (Portuguese)
• Beata (beh-AH-tah, Czech, Danish, German, Italian, Polish, Scandinavian, Slovak, Spanish)
• Daria (DEHR-ee-ah, English; DAR-ee-ah, Croatian, English, German, French, Italian, Polish, Spanish)
• other forms include: Darija (Croatian, Serbian, Slovene), Darya (Russian), Tarja (Finnish)
• Inga (INg-ah, Swedish; ING-gah, Croatian, Danish, German)
• Czech, Finnish, & Frisian form is Inka. 
• Isadora (iz-ah-DOHR-ah, English; eez-ah-DOHR-ah, Italian, Portuguese, Swedish)
• other forms include: Isidora (Greek, Macedonian, Russian, Serbian, Spanish), Izidora (Hungarian)
• Mireille (mee-RAY, French)
• other forms include: Mireia/Mireya (Catalan, Spanish), Mirèio (Occitan), Mirela (Croatian, Romanian), Mirella (Italian, Scandinavian)
• Olga (OHL-gah, Bulgarian, Czech, German, Hungarian, Polish, Portuguese, Romanian, Russian, Scandinavian, Spanish)
• other forms include: Áile (Sami), Helga (German, Scandinavian), Hella (Scandinavian), Olgica (Croatian, Serbian), Laila (Finnish, Scandinavian)
• Ottoline (AH-toh-leen, English)
• other forms include: Oda (German, Scandinavian), Odalis/Odalys (Spanish), Odette/Odile (French), Otilia (Romanian), Ottilia (Swedish), Ottilie/Ute (German), Otylia (Polish)
• Petra (PEH-trah, Bosnian, Bulgarian, Czech, German, Greek, Hungarian, Russian, Serbian, Scandinavian, Slovak, Slovene, Spanish)
• other forms include: Perrine (French), Petroula (Greek), Piera/Pietra (Italian)
• Romana (roh-MAH-nah, Czech, Croatian, German, Italian, Polish, Slovak, Slovene)
• other forms include: Romaine (French), Romána (Hungarian), Romina (Italian, Scandinavian), Romola (Italian)
• Sabina (sah-BEE-nah, Czech, Croatian, Italian, Polish, Russian, Scandinavian, Spanish)
• other forms include: Sabien (Dutch), Sabine (French, German, Scandinavian), Savina (Italian), Szabina (Hungarian)
• Tecla (TEH-klah, Catalan, Italian, Portuguese, Spanish)
• other forms include: Thecla (Dutch), Thekla (German, Greek), Tekla (Polish, Russian,, Scandinavian)
• Zita (ZEE-tah, Czech, French, Hungarian, Italian, Latvian, Portuguese, Slovak; TSEE-tah, German)
• Polish form is Zyta.