- Josef Schicho (Linz)
- Algebraic Geometry
- 1st Feb 2001 to 28th Feb 2001
- Renate Schleidler (Calgary)
- Cryptography
- 23rd Jan 2008
- Johannes Graf von Schmettow (Dusseldorf)
- Comp. group theory
- 29th Jul 1991 to 30th Oct 1991
- 1st Aug 1992 to 1st Oct 1992
- Csaba Schneider (UWA)
- Group Theory
- 1st Dec 2001 to 15th Dec 2001
- Gerhard Schneider (U. GHS, Essen)
- Representation Theory
- 15th Oct 1991 to 15th Mar 1991
- Jasper Scholten (Leuven)
- Arithmetic Geometry
- 1st Dec 2005 to 28th Feb 2006
- 2nd Sep 2006 to 1st Sep 2007
- Frank Schreyer (Saarbrucken)
- Algebraic Geometry
- 1st Sep 2005 to 1st Oct 2005
- James Shank (Kent)
- Invariant theory
- 25th Nov 2013 to 14th Dec 2013
- Gary Sherman (Terre Haute)
- Math. Education
- 4th Mar 1992 to 6th Mar 1992
- Charles Sims (Rutgers)
- Group Theory
- 27th Nov 1999 to 11th Dec 1999
- Shavak Sinanan (University of Warwick)
- Comp. group theory
- 30th Apr 2010 to 8th Jun 2010
- Mike Slattery (Marquette University)
- Comp. group theory
- 15th Jun 2013 to 17th Jul 2013
- Mark Stather (Warwick)
- Comp. group theory
- 19th Feb 2005 to 13th Mar 2005
- Damien Stehlé (CNRS, Lyon)
- Lattices
- 29th Jan 2006 to 28th Jan 2007
- 10th Nov 2007 to 20th Jan 2008
- 19th Jul 2009 to 30th Jun 2010
- Andreas Stein (Calgary)
- Cryptography
- 4th Feb 1999
- William Stein (Harvard)
- Modular Forms
- 1st Apr 2000 to 29th Apr 2000
- 8th May 2001 to 31st May 2001
- 2nd Jun 2003 to 30th Jun 2003
