"Blessed" Alan de la Roche, O.P. (1428-1475) was a 15th Century friar who is considered to be the restorer of the Dominican Rosary. Although Alan has no official Church feast day, he is unofficially honored on September 8th, which is also the feast for the Nativity of Mary.
Blessed Alan stressed the 15 mysteries of the Dominican Rosary, rather than the alternative of 50 clauses of the Carthusian Rosary. Moreover, the 150 Hail Marys imitated the 150 psalms of the Old Testament, which harkened back to the proto-origins of the lay Marian psalter. Blessed Alan was successful at renewing popular devotion to the Rosary and reinvigorating the Confraternity of the Rosary. The Confraternity featured "after death" benefits for Rosarians. Thus Blessed Alan de la Roche may be considered one the greatest champions of the Rosary to ever live.
H/T: Donald Calloway, Champions of the Rosary (2016)