Marcus Garvey, a highly influential leader of African-American philosophy and politics in the early 1900s, is largely thought of as a man who worked alone, though this isn't entirely true. He was involved with and led a number of organizations and businesses, which obviously had him collaborating with other thinkers a lot of the time. One of the things he is most known for is founding the Universal Negro Improvement Association and African Communities League, or UNIA.
One important member of the UNIA was Henrietta Vinton Davis, who was elected the International Organizer of the organization. She worked with Garvey, and he deemed her the "greatest woman of the Negro race today." Other important members of the UNIA that collaborated with Garvey included Gabriel Johnson, G. O. Marke, and J. W. Eason.
Garvey also worked alongside members of other organizations that had varying degrees of connections to the UNIA. The Black Star Line was a shipping company that had a number of higher-ups that worked with Garvey, who was the President. The Black Cross Nurses was a division of the UNIA for women, created by Henrietta Vinton Davis, which served the purpose of making women feel welcome in the UNIA, something that Garvey strove for.
Other collaborators, both groups and individuals, are quite surprising. Earnest Sevier Cox, a white nationalist that collaborated with Nazis, was a friend of Garvey. The UNIA supported Cox's books, and Garvey even put an ad for Cox's White America in one his own books. Their views both stated that whites and blacks should be separated, and they agreed that blacks would be better off if they migrated back to Africa. Garvey is also known for controversially working with the KKK, even meeting with an Imperial Wizard in 1922.
So, in short, yes, Garvey collaborated with plenty of people. Within his own groups, he worked alongside others and even met up with white supremacists that agreed black people should not be in America. Good luck!