U45

U45 may refer to:
 * Aeroflot Flight U-45
 * GERMAN SUBMARINE U-45, various vessels
 * HMS Wild Goose (U45), a sloop of the Royal Navy
 * Icositruncated dodecadodecahedron
 * Small nucleolar RNA SNORD45
 * U45, a line of the Dortmund Stadtbahn