Easter and its related holidays are moveable feasts, not falling on a fixed date; its date is computed based on a lunisolar calendar (solar year plus Moon phase) similar to the Hebrew calendar.
Epiphany also called as Baptism of Jesus, Three Kings Day, Denha, Little Christmas, Theophany, Reyes.
The Easter Bunny is a popular legendary anthropomorphic Easter gift-giving character analogous to Santa Claus in American culture.
Grandparents' Day is a secular holiday celebrated in various countries. Here's HQ blissful illustrations for National Grandparents Day.