This is not in the context of the Crusades per se, but yes, there were legendary figures in the Islamic tradition who took part in holy war against the Christians. I'm only familiar with some of the Turkish ones, so it is to them that I'll turn.

Western Anatolia in the early fourteenth century was an anarchic region due to a breakdown in the authority of the Byzantine and Seljuk states. Power increasingly passed into the hands of local warlords, who rallied warriors to their side to fight for loot, glory, and for the sake of the faith. Historians debate the relative importance of these motivations, but they were certainly all present to some degree. The warriors on the Muslim side, known as gazis, took part in an oral tradition of warrior epics, a form of storytelling which had deep roots in the Islamic world, drawing on tales detailing the military exploits of the Prophet Muhammad, and his uncle and son-in-law Hamza and Ali. Gazi narratives told of the exploits of skillful warriors who won fame and fortune fighting on the frontier between the worlds of Christianity and Islam, but were not always as straightforward as one might expect.

Oftentimes warrior figures would be depicted as following in the footsteps of the subjects of earlier legends: thus the story of Danişmend Gazi begins with a description of an earlier Arab warrior, Seyyid Battal Gazi, and laments that the gazi tradition has died since his time, only for it to be revived by Danişmend - the implication being that the young men hearing the story should themselves take up arms to revive the tradition of Danişmend as told by the legend. Certain motifs linked the stories of different gazis together - several different heroes encounter and ride Aşkar, the immortal horse of the Prophet Muhammad's uncle Hamza, or wield his weapons. All of the legends revolve in some way around the protagonist and his followers' efforts to expand the abode of Islam and win converts. Many such converts become close companions to the hero - the best friend of Seyyid Battal Gazi is a former Byzantine Christian, while Danişmend Gazi is joined by an unmarried Christian couple who convert to Islam and both become warriors by his side - thus the legend includes a female fighter who is not only as skilled as the others, but also engaging in a romantic relationship! Clearly these stories did not always reflect what we think of as "Islamic orthodoxy." Yet they had immense cultural appeal. The tomb of Seyyid Battal Gazi was even "discovered" near Eskişehir in the twelfth century and developed into a cult center.

Probably the most famous of these legends are those found in the Book of Dede Korkut, which exists now in English translation. One story follows the gazi Kan Turalı and his exploits on the frontier with Trebizond. After finding his way to the imperial court, he falls in love with the Byzantine lord's daughter, and requests from him her hand in marriage.

The king said: "This young man talks fast. See if he has any other skill. Undress him naked as he was newly born from his mother." They undressed him. Kan Turalı wrapped his thin, gold-embroidered cloth around his waist. They took him and led him to the arena.

The girl was watching from the kiosk. When she saw him, she almost fainted and began to tremble in excitement. Her cat miaoed, and she began to salivate like a sick calf. She addressed her girl companions, saying: "I wish that Almighty Allah would fill my father's heart with mercy and that he would give me to that young man.

The moral of the story is clear: one look at a gazi is enough to melt a Greek princess's heart. It's easy to imagine how stories like this could be used to instill morale in the breasts of young men looking for adventure, most of whom would presumably be unmarried. The story is then flipped on its head when the princess reveals her superior martial skill, saving them both from the traitorous Byzantine lord and allowing them to escape back to the gazi camp, where they are married - a humbling reminder not to be too hot-headed.

One of my favorite scenes involves Karajuk the shepherd, fighting off an army of infidels who attack him in a field:

The strong and bold shepherd, Karajuk, placed a stone in his sling and hurled it at them, knocking down two or three of the infidels. With a second stone he slung he knocked down three or four and frightened the infidel host. Karajuk the Shepherd knocked down three hundred of the infidels with the stones he hurled at them from his slingshot. His two brothers, however, fell as martyrs to their arrows. When Karajuk ran out of stones, he placed sheep and goats in his sling, and each time he hurled an animal at the enemy he knocked down four or five of them. The infidels' eyes were filled with fear, and the world became a dungeon for them. They thought that the shepherd was going to kill them all, and so they fled.

None of the legends survive to us in the form they would have taken during the heyday of frontier warfare. Rather, they were only transferred into writing after the frontiers were closed. This is because the frontier warriors were always a force standing in opposition to state centralization - as a military force, they would have been one of the first targets that a strong state would attempt to control. As Cemal Kafadar notes, "Whenever the central states believed they had reined in the centrifugal energies of the marches, they were keen to patronize the recording of frontier lore, both appropriating and taming once-rival traditions." As with all oral traditions, they likely changed over time and were adapted the milieu in which they were told, before finally being put into writing and passed down to us.

Cemal Kafadar provides an excellent overview of these legends and their use as sources for the history of fourteenth-century Anatolia in Between Two Worlds: The Construction of the Ottoman State (Berkeley: University of California Press, 1995), pp. 62-90.