Siim is an Estonian masculine given name and may refer to:
Siim Avi (born 1984), Estonian politician and lawyer
Siim Kabrits (born 1979), Estonian politician
Siim Kallas (born 1948), Estonian politician
Siim-Valmar Kiisler (born 1965), Estonian politician
Siim Liivik (born 1988), Estonian-Finnish ice hockey player
Siim Luts (born 1989), Estonian professional footballer
Siim Roops (born 1986), Estonian professional footballer
Siim-Tanel Sammelselg (born 1993), Estonian ski-jumper
Siim Sellis (born 1987), Estonian cross-country skier
Siim Tenno (born 1990), Estonian football midfielder
Siim-Sander Vene (born 1990), Estonian professional basketballer
As a surname:
Andres Siim (born 1962), Estonian architect
