First Appearance: Black Knight #1 (May 1955).
Appearances: Black Knight #1-5.
Years Active: Latter half of the 12th century C.E.
The Crusader is El Alemain ("the hawk"), a Caucasian Saracen who fights alongside Richard Coeur-de-Lion and the other Crusaders in the Third Crusade (1189-1192 C.E.). El Alemain is clearly a Caucasian, but he dresses in Saracen (the term that the Crusaders used to describe Muslims, although strictly speaking it applied only to the people of Northwest Arabia) clothing (robes and a Saracen headdress, rather than a helmet) and uses the "invincible" Saracen Blade, which he won at the lists in Al Bahar. (Whether the Saracen Blade, a scimitar, is actually magical is never revealed.)
His origin is somewhat interesting, although it's naturally a mystery to the general fighting men of Richard Coeur-de-Lion. The Frankish Mrs. O'Dare (a Frank with an Irish name?) was captured, along with her infant son, by the Saracens years before the events of the Crusader's stories. The son, El Alemain, is raised by the Saracens to be a Muslim, but (of course) always feels that his sympathies and affections lie elsewhere, and when a plague-ridden ship of Crusaders runs aground, Alemain matches amulets with Sir John O'Dare and discovers that he's a) a Frank and b) brother to Sir John. Sir John dies soon afterwards of the plague, and Alemain vows to carry on Sir John's work and joins Richard Coeur-de-Lion's forces as a Crusader, even fighting against Saladin himself at one point.
The Crusader is held in esteem by the other Crusaders, especially Richard, who is described as having a "weakness for fighting men." That may be the main reason that the Crusader is regarded so highly by Richard, but I doubt it. In at least one story the Crusader saves Richard's life by foiling an assassination attempt against him (a long-range arrowshot from, I kid you not, a grassy knoll). The Crusader's arch-enemy is the Duke of Montfort, who aims to kill Richard and take control of the Crusade, thus gaining all the glory for himself.
The Crusader is indeed a doughty warrior, and his skill is enhanced by his "Saracen blade," whose origin is but which is a "blade of worth" and which is "invincible in the hand of a man whose soul is clean."
Notes: I'm calling El Alemein "Crusader (I)" because of the modern day supervillain "the Crusader," who properly should be "Crusader (II)." The stories generally depict Richard and the other Crusaders as the good guys, while omitting little things like Richard's homosexuality ("weakness for fighting men," indeed) and the various atrocities that the Crusaders engaged in. I'm not surprised by this--the stories were published in the 1950s, after all--but such things are worth noting.