An excerpt from an obituary in the LA Times:

For Doris Tennant Westcott, class of 1930, was the school's first Helen of Troy.

Westcott, who died May 16 at age 98, will be honored Wednesday at a memorial service at the university, where she made national headlines in 1928.

An active presence on the USC campus, Westcott was elected Helen of Troy in 1928 and again the next year.

As Helen of Troy, she represented the school at social functions and was queen of the annual women's Hi-Jinks program, which was sponsored by the school's YWCA and part of the annual homecoming festivities, said Claude Zachery, an archivist at USC.

The Hi-Jinks was an evening of song, dance and dramatic sketches presented by sororities and women's organizations, and staged at Bovard Auditorium.

Assisted by the Amazons honor society, she took part in the program's prologue by opening the gates of Troy. She also would ride on a float in the homecoming parade.

Years later, she remembered that when she needed a costume for her debut as Helen, someone "took the green velvet draperies from the Elisabeth von KleinSmid Residence Hall and made me a robe for the affair."

USC's teams are, of course, the Trojans ... now, while trying to figure out whether she might have attended the Rose Bowl when it involved chariot races (I don't think it's mathematically possible), I came across this very interesting (and expensive) poster (click on it for a larger version) ...