R'alka Grenn-Emerson is a fictional character in 2th century Starfleet.

A most charming female Caitian and a professional Starfleet officer since 2374, Grenn quickly rose up in ranks and positions, displaying brillant tactical and administrative skill, which led her to the position of USS Excelsior's (NCC-2000-C) Commanding Officer and Task Group Charlie Commanding Officer in rank of Commodore, which she held until June 13, 2381, when she retired, handing over command of Task Group Charlie to Captain James S. Wilk of USS Cox (NCC-78612-A) and the command of the Excelsior to her Executive Officer, Lieutenant Colonel K'esara Rik'u.

Upon retirement, which she spends on Deep Space 7, she was promoted to Rear Admiral.