Nitecore NU25 2022 version, this one uses USB-C and is a little brighter than the old version, though some people feel it contains design regressions
Fenix E01 v2, 1AAA, shortest multi-level 1AAA that I know of offhand, just a few mm longer than the Skilhunt E3A. The E3A is great but it is set to a quite high brightness level, giving limited runtime.
Suggested additions:
Nitecore HA11, very practical and affordable lightweight 1AA headlamp, http://parametrek.com/blog/ha11.html
Nitecore NU25 2022 version, this one uses USB-C and is a little brighter than the old version, though some people feel it contains design regressions
Fenix E01 v2, 1AAA, shortest multi-level 1AAA that I know of offhand, just a few mm longer than the Skilhunt E3A. The E3A is great but it is set to a quite high brightness level, giving limited runtime.
Photon II and Photon Freedom, enduring classics