Is there a special number different from $e$ and $\pi$ for limit in Mathematics?

Question

Is there a special number other than $e$ and $\pi$ which describes an interesting limit in Mathematics?

I searched, but I could not find it.

Answer 1

There is $\gamma$ for Euler Mascheroni constant see Link1

Another one is Feigenbaum constant $\delta$ see Link2

Answer 2

The "golden ratio", $\varphi$, is the limit of the ratios of successive terms in the Fibonacci sequence.

Answer 3

There is Apéry's constant, i.e., $$ ζ(3) = 1.202056903159594285399738161511449990764986292 $$ It is famous in number theory; the values $\zeta(2n+1)$ for the Riemann zeta function are of special interest. $\zeta(3)$ is the limit $$ \zeta(3)=\lim_{n\to \infty}\left(\frac{1}{1^3}+\cdots + \frac{1}{n^3}\right). $$