What is the first name of Marshall and Lily's first son?

Marshall and Lily’s first son is named Marvin. He is born near the end of season seven, in the episode “The Magician’s Code – Part 1,” after Lily goes into labor unexpectedly early.

The name honors Marshall’s late father, Marvin Eriksen Sr., whose death in season six deeply affects Marshall. Barney also negotiates a role in the naming: because Marshall arrives at the hospital with Barney’s help, Barney gets to choose Marvin’s middle name, producing the joke-filled full name Marvin Wait-for-it Eriksen.

Marvin is not Lily and Marshall’s only child. The series finale reveals that they later have a daughter named Daisy and a third child whose name and gender are not revealed. A common mix-up is confusing Marvin Eriksen with Marshall’s father, who is also named Marvin; the son is named after him. Marvin’s birth is a major turning point for the couple and helps establish their family life beyond the original apartment-centered storyline.