WASHINGTON — President Trump’s point man on Israeli-Palestinian negotiations is a longtime Trump Organization lawyer with no government or diplomatic experience. His liaison to African-American leaders is a former reality-TV villain with a penchant for résumé inflation. And his Oval Office gatekeeper is a bullet-headed former New York City cop best known for smacking a protester on the head.

Every president sweeps into office with a coterie of friends and hangers-on who sometimes have minimal experience in the arcana of the federal government. But few have arrived with a contingent more colorful and controversial than that of Mr. Trump, whose White House is peppered with assistants and advisers whose principal qualification is their long friendship with Mr. Trump and his family.

There is Jason Greenblatt, the former Trump Organization lawyer, whose portfolio now includes peace in the West Bank, international trade deals and relations with Cuba. Omarosa Manigault, whose star turn on “The Apprentice” propelled the show’s breakout first season, is now among about two dozen aides with the rank of assistant to the president — and one of the few with walk-in privileges for the Oval Office.

Most other staff members must go through Keith Schiller, who rose from part-time security guard at the Trump Organization to its director of security. Mr. Schiller is now the director of Oval Office operations, controlling physical access to a president whose whims and frustrations routinely send aides throughout the building scurrying to deflect, defend and justify.