Pretty sure there's more Summons from FFs Past than what even Ultimatecalibur has listed. Some of them got demoted to Dungeon/Raid Bosses (Diablos & Fenrir), some got planted (Sylph), and some became Mounts (Hydra/Syldra & Fenrir).

Also can someone link to where they retconned Snowcloak's Fenrir into not being "THE" Fenrir? The minion and mount were specifically stated not to be THE Fenrir in the item/companion descriptions, but I don't ever remember hearing that for the Snowcloak boss?