UML 2.1 Collection
A collection of notation elements for creating UML 2 class, activity, use case, sequence, or component diagrams. It's a rather large stencil, but it contains most UML 2.1 elements. A tool converting Eclipse Java packages to UML class diagrams using this collection can be found on the linked website. Version history:
1.11 (Jun 7, 2017): Lot of minor improvements
1.5: Adjusted font size to match diagrams created by JavaToOmniGraffle.