The letter is U

Inez Tysdal to Les Udell
Brett Udy to G Uhrig
Gregory Uhrig to William Ulmer
Anna Ulrich to Greg Underberg
Pat Underberg to Reo Underwood
Roy Underwood to Allen Unverzagt
Dave Unverzagt to G Urbanek
George Urbanek to Steve Urbom
Alejandro Urena to Fred Urutia