Abraham Peter Carl Siebel (13 January 1836 – 9 May 1868) was a German merchant, poet, and friend of Karl Marx and Friedrich Engels.

From 1852, Siebel was associated with the literary journal Morgenblatt für gebildete Leser (Morning paper for educated readers) and its editor Hermann Hauff.

Between 1856 and 1859, he spent a considerable amount of time travelling in Berlin and Manchester, where he met Friedrich Engels in 1859[3] and Wilhelm Wolff.

[10] Shortly after his return from Madeira, he died of consumption in Elberfeld on 9 May 1868—he had lost weight quickly in the fortnight before his death, and was planning to travel to the Rhine.

[14][verification needed][15] German politician Johann Viktor Bredt called him a "poet by divine grace" in 1937,[16] while Friedrich Engels summarised him in a letter to Jenny Marx on 22 December 1859: "Give me Siebel any day; he may be a rotten poet, but he does at least know that he is a thorough humbug and all he asks is to be allowed to advertise himself—nowadays a necessary procédé [process] without which he would be a complete nonentity.

"[17] The poet Eduard Mörike expressed negative opinions about the quality of his poetry in a letter to Karl von Grüneisen on November 17, 1860.