The bronze bust has withstood two world wars and a global pandemic, but it has recently disappeared from its plinth, prompting an appeal to find it.
Janet Finch-Saunders, the Senedd member for Aberconwy, said she was “heartbroken” by the disappearance.
Ms Finch-Saunders said the alleged theft was “an attack on [the town’s] shared heritage”.
“I echo the fears expressed by local councillors that the statue may have been taken with the intent of melting it down for scrap,” she said.
“This would be an unimaginable loss of cultural and historical value, and we must do all we can to prevent it.”
The bust was erected in the town’s Happy Valley gardens in 1890 to belatedly commemorate the late monarch’s golden jubilee.
Ms Finch-Saunders said the bust had been “a steadfast observer of [Llandudno’s] growth and change for over a century”.
“It is a part of Llandudno’s soul, and we must work together to bring it back to its rightful place,” she added.
A representative of Llandudno Town Council said in a statement they were “very saddened” by the disappearance.
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“This community asset has been much appreciated by residents and visitors since 1890,” said councillor Donald Milne.
“Barriers have been erected around the monument while the plinth is being assessed for repair.”
A spokesperson for North Wales Police said the incident was being investigated and asked anyone with any information to get in touch.
