Aelfan Slayfell is a Space Marine of the Space Wolves Chapter. A member of the Wolfblade, he was assigned, along with Godric Widdowsyn, to guard the Navigator Itsobal Belisarius while he was stationed on the planet Arkhona.
When the Tyranids invaded Arkhona's system, the elders of House Belisarius decided to recall all their personnel on the planet and the Wolfguard joined their charge aboard the House's ship, the Belisarius Indomitus, bound for the safety of Terra. Disaster struck, however, as the Indomitus was boarded as it tried to leave the system, by the Skrullboyz Freebooter band and its crew was easily overrun by the Orks.
As the Freebooters rampaged aboard the ship, Aelfan and Godric fought the Orks to buy time for Itsobal and his Lifeward, Bacauda, to reach the Indomitus' saviour pods. The Wolfguard later rejoined with Itsobal when the Navigator neared the pods, and nearly succeeded in escorting their charge to safety, when they were attacked by the Orks. In the brief and bloody battle that followed, Godric was cut in half by a Deff Dread, though Aelfan avenged his death by destroying the Dredd with grenades. The Dredd's explosion, however, wounded Itsobal and killed Bacauda, who had used his body to protect the Navigator. As Kaptin Radrukk Reddgun, the leader of the Skrullboyz, closed in on their position, Aelfan escaped and hid himself aboard the captured Indomitus while Itsobal was caught by Kaptin Reddgun, who decided to keep the Navigator as a pet.