Regular Expression - Forbid string, of any size, that contains only one character repeatedly

Question

I am looking for a regex that will prevent the insertion of a string, with arbitrary size, that contains only one character repeatedly.

For example these strings are invalid

aaaaaaaaaa
222
bbbbbbbb
@@@@@@@@@@@@@@@@

but these are valid

aaaaaaa2
@@@@@@@@@@@@f
b2222 

I want it for an HTML5 text input:

<input type="text" class="form-control"  placeholder="name" pattern="...">

Answer 1

You can try the following:

^(?!^(.)\1+$).*$

It'd help if you also provide information about which tool you'll be using.