Helen is a feminine given name derived from the Ancient Greek name Ἑλένη, Helenē (dialectal variants: Ἑλένα, Helena, Ἐλένα, Elena, Ϝελένα, Welena), which descends from Proto-Hellenic *Ηwelénā, from a pre-Hellenic or late Proto-Indo-European *Swelénā (a solar deity), ultimately derived from the Indo-European root *swel- (to shine, warm). The name is of uncertain origin. It might be connected to a Greek word meaning "ray of light" or "sunbeam", derived from ἥλιος or hḗlios, the Greek word for "sun". Some sources also connect the name to Hellen, the word meaning Greek. Helen, worshipped as a goddess in Laconia and Rhodes, is a major character in Greek mythology. The name was widely used by early Christians due to Saint Helena, the mother of the emperor Constantine I, who according to legend found a piece of the True Cross from the crucifixion of Jesus when she travelled to Jerusalem. Helen was very popular in the United States during the first half of the 20th century, when it was one of the top ten names for baby girls, but became less common following World War II.