Cape Trafalgar is a point in the south west shore of the Iberian penninsula, north of Gibraltar. This is the place where the famous battle of Cape Trafalgar happened in October of 1805, and Admiral Horatio Nelson defeated the combined fleet of France and Spain, assuming supremacy of the seas for Britian for a century.

Various sources spell it as:

• الطرف الأغر al-Taraf al-Aghar
  This is the contemporary translation in Arabic of Trafalgar, specially when Trafalgar Square is mentioned in the news. For example, this news article in the Arabic BBC.
• طرف الغار Taraf al-Ghar
  This could mean one of two different things, since 'Ghar' means two things in Arabic: 'Cape of the Cave', or 'Cape of Laurels'.
• طرف الغرب Taraf al-Gharb
  This means 'Cape of the West'.

Richard Burton, in his translation of the Arabian Nights, notes in the footnotes that the correct etymology is the last one (Cape of the West), and rebuts Captian Peel that it is the second (Cape of Laurels).

So, neither the current Spanish, English nor Arabic spelling is true to the original name.