Prophet Luqman alaihis salaam, he was black.
The following is mentioned in Imam al-Qurtubi's tafsir, in Surah Luqman.
وَقَالَ لِرَجُلٍ أَسْوَد : لَا تَحْزَن مِنْ أَنَّك أَسْوَد , فَإِنَّهُ كَانَ مِنْ خَيْر النَّاس ثَلَاثَة مِنْ السُّودَان : بِلَال وَمِهْجَع مَوْلَى عُمَر وَلُقْمَان .
He (Sa'id ibn al-Musayyib) advised a black man, "Don't be sad that you are black, for indeed, three of the best people were from Sudan: Bilal, Mihja' the mawla of 'Umar, and Luqman."
وَقَالَ لِرَجُلٍ يَنْظُر إِلَيْهِ : إِنْ كُنْت تَرَانِي غَلِيظ الشَّفَتَيْنِ فَإِنَّهُ يَخْرُج مِنْ بَيْنهمَا كَلَام رَقِيق , وَإِنْ كُنْت تَرَانِي أَسْوَد فَقَلْبِي أَبْيَضُ .
He (Luqman) told a man who was looking at him, "If you see me having thick lips, then indeed gentle speech comes out from between them; and if you see me having black [skin], then indeed my heart is white."