One great example is Spain’s version of Santa Clause, Olentzero. Legend has it that Olentzero was a giant and lived in the Pyrenees with other members of the Jentillak, a clan of giants. The tale states that they saw a glaring light coming from the clouds that only a partially blind member of the Jentillak could manage to see. He knew the light signified the birth of Jesus. Stunned and afraid, the story has it that all the giants left the Pyrenees, but Olentzero stayed to embrace Christianity. Ever since this day Olentzero makes a trip to town each December 24th to bestow great gifts and kindness upon all the children.
There are many variations to the Olentzero traditions and stories connected to him, sometimes varying from village to village. The first written account of Olentzero is from Lope de Isasti in the 17th century: A la noche de Navidad (llamamos) onenzaro, la sazón de los buenos ("To Christmas eve (we call) onenzaro, the season of the good ones". One common version has Olentzero being one of the jentillak, a mythological race of Basque giants living in the Pyrenees. Legend has it that they observed a glowing cloud in the sky one day. None of them could look at this bright cloud except for a very old, nearly blind man. When asked to examine it, he confirmed their fears and told them that it was a sign that Jesus will be born soon. According to some stories, the old man asked the giants to throw him off a cliff to avoid having to live through Christianisation. Having obliged him, the giants tripped on the way down and died themselves except Olentzero.
Other versions have the jentillak simply leaving, with only Olentzero remaining behind to embrace Christianity.