Lyon

Lyon was a Human male Starfleet officer serving in the late-23rd and early-24th century.

Around the turn of the 2300s, Lyon was assigned to the USS Excelsior (NCC-2000) as its navigator. 

Chronology
Lyon's tenure as navigator must be no earlier than 2298 as Pavel Chekov is no longer aboard as first officer and Janice Rand is a full commander.