Julius Grant Martinez is a fitting name for a character in the Warhammer 40,000 universe. Here are some generated names based on your input:

1. Julius Grantus Martianus - A noble Space Marine commander.
2. Martinez the Resolute - An Imperial Guard officer known for his bravery.
3. Julius Grantor, Warlord of the Ashen Legion - A fearsome Ork warboss.
4. Martinez of the Celestial Watch - An Eldar ranger with a storied past.

Feel free to request more names or specify different parameters!