a group of 4 that didn't go on any of the Apollo missions is a terrible category!! that category could literally have been anyone or thing

Excellent work Terry. What a shame Emile Zola, who was shortlisted for the first two Nobel prizes for literature at the start of the 1900's didn't make any of the missions, he would have made a very fine astronaut as would his great grandson Gianfranco Zola (OBE OMRI) the renowned diminutive Italian footballer...
The Tarzan clue did for me, although in hindsight your definition is correct.

My only gripe is the King Kong rhyming slang. Pong is far more commonly rhymed with 'Gospel Song' rather than 'King Kong'.
Otherwise, a good grid.

Ace grid !

Tarzan is not an animal and how is anyone supposed to get the Apollo moon missions group?!

Tarzan is so an animal ! He lives in the jungle.
I thought the moon mission group would be the easiest one to get. But maybe not.

Tarzan isn't actually fictional, but otherwise a well put together grid.
Good work.

Oh Terry, I think you are making the fun

You need GSOH for this! Fun..