Title: Hide Title can be set, but need not be displayed

Show all
Children of: Current Item Current Root Item Current Parent Item

Fallback to Current Item, and
Include Parent... & its Siblings
If Current Root/Parent and no ancestor exists

Starting Level:
Level to start testing items for inclusion

For Depth: unlimited
Relative to the first Filtered item found

Hierarchical   Flat

Include Parent... & its Siblings
Include Ancestors
Title from Parent Item
Only if the "Children of:" Filter returns items

Change UL to OL:
Top Level   Sub-Levels

Note that since WP v3.6 does it automatically,
"Hide Widget if Empty" is ON for this demo.