Sissi or Sisi may refer to:
- People
- Empress Elisabeth of Austria, known as "Sisi" or "Sissi"; spouse of Franz Joseph I of Austria
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- Works about Sissi
- Sissi trilogy (film) with Romy Schneider:
- Sissi (1955)
- Sissi – The Young Empress (Sissi – Die junge Kaiserin) (1956)
- Sissi – Fateful Years of an Empress (Sissi – Schicksalsjahre einer Kaiserin) (1957)
- Sisi (2009), TV film directed by Xaver Schwarzenberg, with Cristiana Capotondi
- Princess Sissi (1997), French-Canadian animated television series
- Sissi, the Anarchist Empress (Sissi Impératice), a ballet by Maurice Béjart
- Other notable people
- Sissi (footballer) (born 1967), Brazilian football player Sisleide do Amor Lima
- Sisinio González Martínez (born 1986), Spanish footballer known as Sisi
- Sissi Christidou, Greek television presenter
- Seyhan "Sisi" Soylu, Turkish television personality
- Localities
- Sissi (Chad), a small place in Chad (10°32' N, 18°24' E)
- Sisi, Crete, a place in Crete, Greece
- Other uses
- Elisabeth Delmas, nicknamed 'Sissi', a character in the French animated television series Code Lyoko
- Sisi (drink), a Dutch fruit-flavoured beverage
- Sissi (Finnish light infantry), a specialized type of Finnish soldier