What are "chaos champions"?

[Gingy]

Are they chaos Lords? Exalted heroes? Specific characters featured in the CoC DLC? Daemon Princes?

I see the term mentioned a lot but there's never any definitive... definition

[Conflagration]

All of the above, it's pretty much a catch-all term for warriors favoured by Chaos. There is of course the unit Aspiring Champions, who're the elite Chosen - just below Exalted Heroes.

[Lain]

in the dlc? it adds a bunch of units across most tiers, so some early mid and late game stuff
and gives access to some notable legendary lords & normal Lords who are basically chaos lords and daemon princes

[Velber]

any mortal servants who have made a name for themselves serving the chaos gods is usually how i interpret it

[Urinietszche]

Read up the word champion in the dictionary, there is more to it than just winning chess competition

[Enelith]

You could google it as well, considering Warhammer is both a TT & TRPG game you know.

https://warhammerfantasy.fandom.com/wiki/Category:Chaos_Champions
https://whfb.lexicanum.com/wiki/Chaos_Champion
https://warhammer40k.fandom.com/wiki/Champion_of_Chaos (w40k version, but it's same anyway...)

[Defmonkey]

Not ginger from what i can tell