Olli: Name day
Name Day List: Olli
| Country | Day | Month | Names |
 Estonia | 31 | May | Helga, Helge, Helgi, Helja, Helje, Heljo, Helju, Elga, Olga, Olli |
 Finland | 29 | July | Olavi, Olli, Uolevi, Uoti, Oula |
Name Day List - similar names (Olli)
| Country | Day | Month | Names |
 Ukraine | 5 | January | Apollinaria, Teon |
 France | 9 | February | Apolline |
| Estonia | 18 | April | Valdemar, Voldemar, Valdek, Valdeko, Valdo, Valdu, Valdur, Valmar, Valmer, Volmer, Volli |
 USA | 11 | July | Alivia, Helga, Livia, Olga, Olive, Ollie, Oliver, Olivia, Quentin, Quincy, Quinn, Quintina, Quinton |
 Austria | 20 | July | Apollinaris, Bernhard, Margaretha |
 Denmark | 23 | July | Apollinaris |
| Ukraine | 23 | July | Apollinary |
| France | 12 | September | Apollinaire |
| USA | 7 | November | Engelbert, Graham, Hollis, Holm, Holmes, Holt |
| USA | 12 | November | Colan, Colin, Colleen, Collin, Cullan, Cullen, Culver, Kiley, Kyla, Kyle, Kylee, Kyleigh, Kyler, Kylier |
| USA | 25 | December | Anastasia, Noel, Noelle, Hollie, Holly, Jesus, Stacey, Stacie, Stacy |