Mathematicians working in related fields include

Michel Crouzeix

Webpage   

Luca Ferracina

Doctor's thesis (2005): "Monotonicity and boundedness in general Runge-Kutta methods", can be found via the website of the Mathematical Institute  or Leiden University.   Webpage

Inmaculada Higueras

Webpage  

Karel in 't Hout

Reserch area: Analysis and development of numerical methods for various classes of (partial, delay and ordinary) differential equations with applications to financial mathematics. Webpage

Willem Hundsdorfer
With sadness, I mention that my dear colleague—and former PhD-student—Willem Hundsdorfer passed away in November 2017.

Research field: Numerical methods for stiff ordinary differential equations and time-dependent partial differential equations.
Webpage

Cesar Palencia

University of Valladolid

Steven Ruuth

Main reserch area: scientific computing, (1) PDEs on Surfaces, (2) Time Evolution for PDEs and (3) Interfacial Dynamics. Webpage 

Chi-Wang Shu

Research interests include:  Numerical solutions of conservation laws and in general convection dominated problems. Webpage