Which lightweight Linux Distribution with GUI would you recommend for an old Laptop ?

Being lightweight or not doesn't depend on the distro but the desktop manager (the graphic interface). Unlike Windows, the graphic in Linux is separated from the system so you can use different desktop managers on the same distros.

The lightest DE is LXQT but it's pretty barebone, XFCE has more features while still being very light, avoid GNOME and KDE.

That being said, I suggest you try Linux MX XFCE or Mint XFCE first, if that's not light enough for your liking, try Lubuntu, that's Ubuntu with LXQT as default DE.

@ulu_mulu
I can also recommend LXDE which is very lightweight. That's what I installed on my dad's old single core laptop.
@Fungus

Mint XFCE or Lubuntu. I would try Mint Cinnamon first, to see if it runs properly. If not, try one of the above.

Mint xfce! Its a res spell for old hardware

Mint XFCE

This is first stop, if this is slow than try something else.

My guess is it will be too slow, but it is worth a try.
- exactly the way I see it too it's the lightest of the no compromise linux environement, after that you're starting to see the gears

Debian with LXQt. Good luck.

Debian XFCE

something that runs xfce

Manjaro XFCE ftw

Lubuntu
Linux Lite
Zorin OS Lite

If that is still not enough you could try Chromeos Flex. It's not Linux but it could at least maybe make your old Laptop usable again for casual web browsing.

I spent a few weeks learning the arch installation for my old laptop and it's had the same installation now for about four years. It's awesome and I have only the packages I need, no more, no less.

You can use quite a number of "underlying" distributions, it mainly depends on what you like (Arch-based ones, Debian-based ones, etc).

As a desktop environment, have a look at XFCE or LXDE.

I daily drive a netbook and I use Debian 12 with KDE Plasma on it. The netbook is a 2014 ThinkPad 11e with a Celeron and 4GB of RAM. I find it comfortable for writing and even some Python and JavaScript development. I remote into my servers/cloud infra for more intense development tasks.

+1 for upgrading whatever you can before installing linux. An SSD in particular will go a long way to make it feel snappy.

Artix or archbang. For the debian side, antix linux.

Thank you for all the suggestions, I don’t have access to the laptop right now, so I can’t get the specs, I’ll try to post them tomorrow

I would just buy a cheap RAM stick and install one of the mainstream distrobutions with KDE Plasma on it. You can turn off most of the desktop effects and unnecessary background services.

You could try out BunsenLabs, it's loads of fun and reasonably lightweight. Basically Debian with a few tweaks.

Permanently Deleted

ZorinOS Lite

Idk your laptop's specs but I've been running Arch with XFCE on my Thinkpad T400 for a while now and it was decent enough to do college assignments, take notes, watch videos and stuff like that a year or two ago. Debian is also decent nowadays, and heard good things about Peppermint but I have no experience with it.

Truth is, it doesn't really matter as long as you use a lightweight DE like XFCE, lxqt or cinamon. The thing that will inevitably kill older machines is the modern JS heavy web. Youtube and Reddit were really pushing the limits of that old machine sometimes but it struggled through.

Mx Linux or Antix Linux. If you need more GUI and handholding try OpenSuse Leap

I have successfully run Arch with Openbox as WM on machines even older than that. Arch has a learning curve, though.

And therefore it should not be recommended to Linux beginners... It is not a beginner distro.
- There is no such thing as a "beginner distro". There are distros that need little to no intelligence to set up and maintain. Arch needs you to read and follow instructions. It is a myth that it is impossible for beginners to use Arch. There are several good installations instructions in the wiki, select one and follow it till the end.
  
  There are also plenty of Arch derivates that preconfigure the system for you.
@Dirk @Fungus
Arch + aur is a little bit too much in my opinion. Old PC = old slow hardware. Some of aur pacages are basicly compile instructions. Also you won't benefit as much from rolling release.
For GUI stay away from GNOME as it is resource hungry. KDE claimes to be a lot better but honestly it is still a very polished flashy expirence out of the box.
Learn using KDE, atempt to replicate using window manager like AwesomeWM.
You will "waste" resource only for what is a mass have for You.
- @mrXYZ
  Unless you're doing something very unusual, you're not going to end up with many AUR packages. I've run Arch on SBCs without much trouble.
  
  There are severely steps in between Gnome/KDE and Awesome. XFCE and Enlightenment are more user friendly options that are still quite lightweight.
  @Dirk @Fungus

I recomend you to max out the ram, replace hdd with ssd and thermal paste while cleaning the dust with compressed air. It'll work with Linux faster than ever.

You can try out different distros in Live-mode (no installation/format requirements) if you just format your biggest usb stick with Ventoy2Disk and drag and drop any .iso-file you want to try: https://www.ventoy.net/en/doc_ventoy2disk.html

I don't say what distro you should use. But if you're considering Linux Mint then try LMDE5 instead and here's why: https://forums.linuxmint.com/viewtopic.php?t=374128

Thank you for your recommendation, but I really don’t want to spend any money at all on it. I’d like it to be a toy to learn a bit about Linux, not a daily driver 😁
- The 128 gb ssd's are like 20-30 bucks and used probably even cheaper. Used ddr2 or ddr3 ram sticks are like 5-10 bucks each.
  
  Thermal paste should be replaced every 2-3 years into every computer. Because the cpu isn't modern nor fast in today's standards, cleaning the dust and replacing the thermal paste will make cpu to thermal throttle way less which means faster run overall.
  
  But obviously the choice is yours and I'm not forcing you. Happy Linux learning times!
- then void linux would be the perfect fit for you
  its highly tinkerable and has a smooth learning curve

MX Linux!

Kind of two parts to this question: Linux for low spec hardware? And beginner Linux?

When I got started with Linux in 2017, I started listening to a lot of Linux related podcasts which was really helpful to get my head around a lot of terminology and Linux technologies. A friend of mine runs Arch so I knew I wanted to get there eventually, but for the first couple of years I ran Linux Mint, then Ubuntu, and for the last year or so I’ve been on Arch.

Regarding the low spec hardware thing: I have an ASUS net-top with a Celeron CPU & 1GB ram & spinning disk HDD. I’ve run mint xfce on it with a lot of success. Tiny core Linux is extremely performant on really old gear, but it’s very old school & different to popular distros

Any (Arch) based distro + Sway

@Fungus I have an old Gateway laptop with a single core CPU which happily runs Zorin (32 bit version). Easy OS for beginners.

by GUI, you mean with GUI installer right ? if yes then i recommend Debian

Specs? How much fiddling do you want to do?

Distro won't matter so much as Desktop Environment. KDE Plasma and MATE are both sensible choices, both very popular, and good for anyone who wants a familiar mouse and window kind of experience.

If it were me, I'd probably just download something like Debian and then set up one of those two DEs (which might even be possible directly from the installer; I can't remember).

Peppermint OS!!!!! running it right now and its SMOOTH! lightweight and looks sexy while doing it!

Void Linux. It doesn't have the heavy SystemD, starts off with a simple XFCE environment.

Not to mention the incredibly fast XBPS package manager.

Definitely not for a Linux beginner, though.
- For a beginner, maybe not. But I'd probably suggest it over something like Arch just because of the excellent installer, amazing community and healthy ecosystem of packages.