using System;

using System.Linq;

using System.Collections.Generic;

public class Program

{

    public static void Main()

    {

        var persons = new List<Person>() 

        {

            new Person { Name = "Maria", Age = 25 },

            new Person { Name = "Paula", Age = 21 }

        };

        var p = persons.First(p => p.Name == "Xaver");

        Console.WriteLine(p == null ? "Person ist <NULL>" : $"Person ist {p.Name}");

    }

    public class Person 

    {   

        public string Name { get; set; }

        public int Age { get; set; }

    }

}

​