1. 最后的晚餐中的13门徒
Some Christian traditions have it that at the Last SupperJudas, the disciple who betrayed Jesus, was the 13th to sit at the table.
传说耶稣遇难前和弟子们共进了一次晚餐。参加晚餐的第13个人是耶稣的弟子犹大。就是这个犹大为了30块银元，把耶稣出卖给犹太教当局，致使耶稣受尽折磨。而且参加最后晚餐的是13个人，晚餐的日期恰逢13日，“13”给耶稣带来苦难和不幸。从此，“13”被认为是不幸的象征，也成为背叛和出卖的同义词。
2. 北欧火神洛基的传说
Triskaidekaphobia may have also affected the Vikings-it is believed that Loki in the Norse pantheon was the 13th god. More specifically, Loki was believed to have engineered the murder of Balder, and was the 13th guest to arrive at the funeral. This is perhaps related to the superstition that if thirteen people gather, one of them will die in the following year.
在北欧神话中，火神洛基(Loki)是诸神中的第13位，他本身邪恶而狡诈。他欺骗并唆使黑暗盲神Hoder害死了自己的兄弟、光明之神 Balder，又成为葬礼上的第13位吊唁者。此后西方就有迷信：如果葬礼中有13个人出席，那么其中一人会在第二年死去。这也是“恐数字13症”的一种由来。
3. 波斯黄道十二宫的传说
Ancient Persians believed the twelve constellations in the Zodiac controlled the months of the year, and each ruled the earth for a thousand years at the end of which the sky and earth collapsed in chaos. Therefore, the thirteenth is identified with chaos and the reason Persians leave their houses to avoid bad luck on the thirteenth day of the Persian Calendar, a tradition called Sizdah Bedar.
古代的波斯人相信天空中的黄道十二星座掌控着一年的十二个月，而每个星座会统治地球一千年。等到十二个轮回结束，天空和大地就会崩塌。因此，第十三就和混乱联系了起来。波斯人在波斯历上的第十三天会外出、以避免厄运，这个传统被称为“Sizdah Bedar”，意思是“十三户外”。
However, the number 13 is not uniformly bad in the Judeo-Christian tradition. For example, the 13 attributes of God (also called the thirteen attributes of mercy) are enumerated in the Torah. Some modern Christian churches also use 13 attributes of God in sermons.
除此以外，不吉利的13还有很多传闻，包括汉莫拉比法典(code of Hummurabi)的第13条法规、十字军东征时的13圆桌骑士以及Friday the 13th(十三号星期五)等等。不过，也不是所有基督教传统的国家都认为13是不吉利的，在某些基督教祭典中还有13信条的仪式.