This chapter approaches the PDE-based image segmentation domain, describing variational and non-variational PDE-based models for static and video image segmentation. The edge-based segmentation of static images is addressed in the first section of the chapter, where our contribution in this field, representing a nonlinear diffusion-based multi-scale edge detection framework, is discussed. Next, the segmentation solutions using nonlinear PDE-based parametric and geometric active contour models are presented in the second section. Our own contributions, representing some geodesic active contours with level-set functions, are also described here. The video image segmentation field is then addressed in the third section. A temporal video segmentation technique proposed by us, which combines a nonlinear second-order PDE-based multi-scale frame analysis to a deep learning-based high-level feature extraction, is discussed in that section.