ハ, ハク, はたがしら, はる
hegemony, supremacy, leadership, champion
JLPT1 G7 S19 F1173
霸 is 雨 rain/natural phenomena + an element combining 革# (stretch tautly) and 月 moon → strain (figuratively "stretch") the eyes to observe the whitish moon spreading over the daytime sky. *Domination* and *dominion* are borrowed meanings. 霸 has been supplanted by the form 覇.
[Full Kanji Etymology List]