Admiral Arthur Bellamy was a Starfleet flag officer from the 24th century. (The Dominion War Sourcebook: The Fires of Armageddon)
Bellamy took command of the Seventh Fleet prior to the Battle of Sybaron. He commanded the fleet during that action and while he lost nearly half his forces and was forced into retreat he succeeded in denying the Dominion from their own objective of attacking Tellar.
He again led the Seventh Fleet in the Battle of the Tibor Nebula with the objective of stopping the Dominion from securing supply lines to launch a third attack on Vulcan. Bellamy and his forces were exhausted and at half strength from their losses at Sybaron and were defeated in the battle.
- Bellamy's fate in the Battle of Tibor Nebula isn't specifically mentioned but given later in the sourcebook the Seventh is under the command of Valerie Umstead it is possible Bellamy was killed at Tibor.