In Russian the sound [h] is a major source of akwkawkwardness. In Russian it's strictly an allophone of the velar sound /x/ (spelled X x), as are all the voiceless fricatives pronounced further back than /x/. However, we do have its voiced equivalent /ɣ/ as a marginal phoneme, together with all the corresponding voiced allophones, especially [ɦ]. Mainly they occur as a result of voicing the /x/ phoneme, but the situation is quite a bit more complicated.
You see, the voiced [ɣ~ɦ] were originally the main allophones of /g/ (spelled Г г) across a vast territory stretching from the Black Sea steppes to eastern Germany. This original allophony is still faithfully reflected by Russian dialects but by no other Slavic language to my knowledge - in Czech and even the other East Slavic standard languages, Ukrainian and Belarusian, the fricative /ɣ~ɦ/ (spelled Г г) and the stop /g/ (spelled Ґ ґ) were and are separate phonemes. Accordingly, some Russian speakers can theoretically distinguish them as well, and it was this voiced fricative that the [h] of Germanic languages, Latin and Greek was expressed. The trouble is, there was and still is no separate letter for it, so it was spelled with the letter for /g/, Г г. You just had to know when to pronounce it as the fricative (most cases being obvious borrowings).
But because for most monolingual speakers the two sounds were allophones, almost all the /ɣ~ɦ/ words eventually came to be pronounced with /g/ (the original survives in a couple of borderline cases). So we write and say Gítler (Hitler), Gugó (Hugo), Bagámy (the Bahamas) etc. Now, with well-established words this isn't a problem, since this is the way everyone says them. But when transliterating the rarer and newer ones, one is faced with the problem of /g/ being miles away from [h]; as a result, its preferred transliteration today is X /x/. This is fine when dealing with a language like English that has no other back fricative phoneme; with Czech and Ukrainian the correspondence it etymological; but when it comes to German or Gaelic with their separate /h/ and /x/ phonemes, this is a source of constant gesitation and akwkawkwardness.
If you ask me, we need to adopt a letter for /h~ɦ/ already.