Pretty much.

I would guess no technically, since The Lancer is defined in relation to the hero.

Metaphorically? Maybe- I can't think of any examples, though. Usually the the Big Bad and The Dragon have a lot more in common than The Hero and The Lancer.

Yeah, but the Dragon is usually seen as a subordinate to the Big Bad. I'm thinking of a character who's at an equal level to the main villain, but isn't the one who takes the lead in their evil schemes.

I suppose the situation would be rare, since you don't see a lot of fictional examples of villains trusting each other like a hero would trust his lancer, least of all in the case of Big Bads.

Never mind, just read the page:)

The funny thing is, my understanding was that the trope/character type was named for the character in Mospeda/Robotech - the "backup" hero, who's more worldly and cynical and reserved than the earnest, naive, hot-blooded young-male-viewer-surrogate capital-H Hero. Thus, Lancer vis Scott Bernard, Han Solo vis Luke Skywalker... the sort also known as the Cool Guy.