Yes, the Tenchi Muyo OVAs that Isekai no Seikishi Monogatari are spun off from. Tenchi and Kenshi are half-brothers.
Part 1, Part 1.5, Part 2, Part 3
Chrome Shelled Regios as previously mentioned. If you haven't seen it, you really should correct that.
Hokuto no Ken (Fist of the North Star), an older series, but really now...it's hard to surpass this level of badassery.
City Hunter, an older series, but Ryo is a total badass while still being down to earth.
Dog Days for a easy going, light-hearted version with middle schoolers. It's a bit underrated, since it really is a fun series.
Again, the Nanoha franchise. Alpha Female(s), but Nanoha isn't nicknamed The White Devil for no reason.