It depends where and for what you are auditioning.
For orchestras in America: 1st movement romantic era concerto (e.g. Tchaikovsky, Mendelssohn, Sibellius, Bruch) and Mozart concertos 3,4, or 5, as well as usually several orchestral excerpts usually listed on a the orchestra's website.
For orchestras in Europe: 1st movement Mozart concerto 3,4, or 5 and 2 contrasting movements of solo Bach (fuges and ciaccone are generally preferred for one of the movements).
For universities/conservatories it varies a lot, but you can usually count on at least the 1st movement of a romantic era concerto, 2 movements of solo Bach, and a virtuostic piece/caprice such as Paganini, ysaye, wieniawski, etc.
Many schools have more, or unique requirements so it is wise to check well in advance.
Hope this helps!