While reading about [name_f]Mariana[/name_f] [name_f]Victoria[/name_f] of Spain (an 18th century Infanta of Spain and later [name_f]Queen[/name_f] of Portugal) I’ve learnt that her name was translated in [name_u]French[/name_u] as Marie-Anne-Victoire. Quite a grand appellation— and the only triple-barrelled name I’ve ever come across!
Have you heard of any other? [name_u]Or[/name_u] are you, perhaps, feeling inspired to create some? 
i know i’m going to now spend the next like twenty minutes trying to come up with some! i’ll come back if i have any luck! 
Marie-Anne-Victoire is beautiful. I haven’t come across any myself.
A few ideas using names from my list:
Mary-Martha-Gail
Valerie-Judith-Agnes
Alice-Ramona-Holly
Rose-Bernadette-Maud
Sarah-Jane-Margaret
Ada-Helen-Frances
Hollis-John-Patrick
Alan-Hugh-Linus
Wilfred-Leo-Thomas
Frank-Arthur-Miller
Edmund-Peter-Vale
Albert-Earl-Henry
the only ones i liked were…
lily-anne-may
luna-belle-rose
elsie-marissa-faye
I haven’t heard of any others. Sadly I don’t think they would work for me because I prefer double middles, which would make five names.
Using one of my combos, [name_f]Imagine[/name_f] Astoria-Cynthie-Jane Middlename Middlename. It would if you triple barrelled shorter names, making a three syllable name and 2 middles. I might try to find some ideas.
I’ve met two people with three first names (though not entireley hyphenated).
The names were quite distinctive (and students at the school I work at) but think of these as close alternatives:
[name_f]Ana[/name_f] [name_f]Flor[/name_f] [name_f]Gilda[/name_f]
Ramla Batul-Noor
Anyhow, some that I’d make, just for fun:
Mabli-Cherith-Sol
Otso-Finley-Jude
Heidi-Rose-Lyra
Rowan-Adair-Marlo
Isolde-Maeve-Yara
Artan-Remy-Jude
I read a story by [name_m]Guy[/name_m] de Maupassant a while ago where the heroine was named Louise-Hortense-Genevieve. [name_m]Long[/name_m] but pretty!
ETA: Apparently the story is The Wedding of Lieutenant Laré 
Marie-Anne-Victorie has such a nice flow to it! I’ve never considered triple barrel names or even heard of any I don’t think. I’m going to try to look at my list and see if any would work…
Henrietta-Pearl-Evelina
Alessia-Ayla-Rue
Adella-Beatrice-Winslet
Lorelai-Delsie-Louella
Lennox-Orion-Sloane
Zephyr-Winslow-Wells
Jasper-Oakey-Winston
The only one I’m liking is Alessia-Ayla-Rue but they all feel like a bit of a mouthful! I’m definitely going to have to keep triple barrel ideas in the back of my mind though 