It's only phyiscal things that can't hurt Juggernaut (and whatever things like heat vision and such are), which leaves him open from attacks from things like magic and power cosmic.
No juggernaut is not the most powerful, But he is Top Tier, If Juggernaut were to use all his power however, He would become a being with so much power he would be a Skyfather level Being.
Only things that can stop Juggernaut is Large doses of Magic and telepathy.
Yet the God blast is A magical attack and Juggs has fought Strange to a standstill before.
#1, Spectre isn't no where near the strongest cosmics. Both Luficer can Michael Morningstar trumps him alone, any day.
And right now, it looks like Lucifer is losing to the Living Tribunal in the: Living Tribunal vs Lucifer thread.
The most powerful non-cosmic eternty would be: Pre-crisis Superman,I guess.
Gender: Male Location: Following the Source of Light.
If by normal, you mean street-level type characters, then no. No normal characters can defeat Classic Juggernaut.
To KO Juggs, you must be able to:
1) Remove Juggernaut's helmet then hit him with a telepathic attack of significant strength.
2) Possess enough raw power to overwhelm the enchantments of Cytorrak. (The list of people who can actually do this is limited to the upper cosmic tier).