We compare different types of regular static, spherically symmetric black holes and discuss their particular type, black universes, which contain an expanding, asymptotically de Sitter T-region, able to model the observed Universe; such models exist in the presence of phantom matter. Next, we consider the stability of static self-gravitating scalar fields with different potentials V (φ) in general relativity. Their general feature is that the effective potential for perturbations is singular at a throat (if any) but generically admits regularization, which in turn leads to regular perturbations of the scalar field and the metric. As examples, we consider some particular black-universe models and find a stable family among them. © Rencontres du Vietnam All rights reserved.