A solo - Just one person. Like the only one who showed up to the part

Just one person. Like the only one who showed up to the party and everyone else was a no-show.

"He did it all by himself. One person. A solo.", @PartyNoShow

"Only one guy showed up. That’s a solo.", @PartyMan123

"A solo is when you’re the only one who actually shows up.", @PartyVibesOnly"