He was portrayed by Erick Hayden.
Marshall was only seen during the SPECTRE meeting in Rome, where he hears of Moreau's reports of the attacks on Hamburg and Indonesia as part of Blofeld's plot to take control of the world's intelligence systems through Max Denbigh's Nine-Eyes program. He would later hear of Dr. Vogel's reports of human trafficking and prostitution.
After Vogel finishes her report, Moreau announces to anyone who would like to fill in for the late Marco Sciarra to kill Mr. White after the failed mission in Mexico, to which Guerra offers to take over. Blofeld then asks if anyone else wants to take over the mission, to which Mr. Hinx arrives on cue.
Marshall then watches as Hinx kills Guerra to ensure that he would do the job pretty well of tracking down Mr. White. Eventually, Blofeld detects James Bond's presence and exposes him, forcing a nervous Bond to escape after killing Lorenzo.
No Time To Die
It was confirmed on an MI6 database that all remaining members of SPECTRE were murdered in a meeting in Cuba when Valdo Obruchev unleashes the Heracles nanobots on them as part of Lyutsifer Safin's successful plan to dismantle SPECTRE. This further implies that Marshall was killed by the nanobots alongside his fellow SPECTRE members; even an imprisoned Blofeld himself suffers the same fate.