(Thanks to John Nagle.)

1. . Hero's mother is a royal virgin;
First son of Empress Maria Fyodorovna. +1

2. His father is a king, and
Eldest son of Emperor Alexander III. +1

3. Often a near relative of his mother, but
Probably not.

4. The circumstances of his conception are unusual, and
No.

5. He is also reputed to be the son of a god.
The Romanov dynasty was, to some extent, worshipped, but not as gods.

6. At birth an attempt is made, usually by his father or his maternal grand father to kill him, but
No.

7. he is spirited away, and
"As Tsarevich, Nicholas did a fair amount of traveling, including a notable trip to the Empire of Japan which left him with a scar in his forehead. A Japanese anarchist had nearly killed him, but Nicholas was saved by the quick action of his cousin, Prince George of Greece." - Wikipedia +1

8. Reared by foster-parents in a far country.
No.

9. We are told nothing of his childhood, but
No.

10. On reaching manhood he returns or goes to his future Kingdom.
Yes; returned to Russia after the trip to Japan. +1

11. After a victory over the king and/or a giant, dragon, or wild beast.
No.

12. He marries a princess, often the daughter of his predecessor and
Nicholas married Princess Alix of Hesse. +1

13. And becomes king.
Nicholas succeeded Alexander III in 1894. +1

14. For a time he reigns uneventfully and
Although Nicholas initially had a good relationship with his relatively liberal prime minister, Sergei Witte, Alexandra (his wife) distrusted him. +1

15. Prescribes laws, but
As the political situation deteriorated, Nicholas dissolved the Duma.
+1

16. Later he loses favor with the gods and/or his subjects, and

Prime minister Pyotr Stolypin and the Emperor were barely on speaking terms, and the Emperor's fall was "widely foreseen". From there, things went downhill. First WWI, then the Bolshevik Revolution. +1

17. Is driven from the throne and city, after which
Led the Russian Army from the German front, without much success.
Abdicated in 1917. +1

18. He meets with a mysterious death
Executed by firing squad in a basement. +1

19. Often at the top of a hill,
No.

20. His children, if any do not succeed him.
He was the last Tsar. +1

21. His body is not buried, but nevertheless
"The bodies of Nicholas and his family were long believed to have been disposed of down a mineshaft at a site called the Four Brothers. Initially, this was true — they had indeed been disposed of there on the night of July 17. The following morning —when rumors spread in Yekaterinburg regarding the disposal site —Yurovsky removed the bodies and concealed them elsewhere. When the vehicle carrying the bodies broke down on the way to the next chosen site, Yurovsky made new arrangements, and buried most of
the bodies in a sealed and concealed pit on Koptyaki Road, a cart track (now abandoned) 12 miles north of Yekaterinburg. Their remains were later found in 1991 and reburied by the Russian government." -- Wikipedia +1

22. He has one or more holy sepulchres.
Canonized by the Russian Orthodox Church in 2000.
Imperial Fyodorovski Cathedral might qualify. +1