No, there are other bosses that don’t deal damage.
King Chuck (Orcsoberfest) – the encounter is mechanic-based and you don’t take direct damage from him.
The Great Schnitzel (Orcsoberfest) – not technically a bosstiary boss, but the encounter is also harmless.
Lord Retro (25 Years of Tibia Quest) – also mechanic-based, you can be kicked/forced out, but you don’t take damage.
There is also the world event in Nimmersatt’s Lair where you don’t take damage, but it’s not a proper boss (no Bosstiary entry/not treated as a boss fight).
Out of these, only King Chuck and Lord Retro can be defeated. On Nimmersatt's Lair event you can also "defeat" it by breaching the wall.