Since we have quite a lot of general threads by now:
- The Giant Auction Thread
- eBay Garbage
- Miscut Cards General Thread
- Show Off Your Error Cards!
- Giant Art thread
Why not one for autographed cards and other Pokémon products as well?
So, I’ll start: here are all autographed cards I have in my collection:
English EX Sandstorm Pikachu autographed by illustrator Mitsuhiro Arita (and authenticated by Beckett):
This was the first signed card I bought. Won it in a PWCC auction for 55 USD. 
Shadowless Red Cheeks and unlimited Yellow Cheeks Base Set Pikachus, both signed by Mitsuhiro Arita (his English and Japanese signatures respectively) and authenticated by Beckett:
Won both of these at the same time, again from PWCC auctions. I wanted to win at least one, but was glad I won both, especially since both the Pikachus and signatures are slightly different.
English #27 WotC Promo Pikachu signed by Veronica Taylor (voice actress of Ash in the English anime):
Veronica Taylor signs, just like Mitushiro Arita, cards pretty often. So her signature isn’t too hard to find in comparison to some other signatures.
Japanese 090/XY-P Promo signed by Imakuni? (an illustrator, but not the illustrator of this artwork):
Was able to win this on Yahoo Japan for a pretty good price (which I can’t remember anymore).
Japanese 068/SM-P promo signed by Ponyta Ishii (host of the official Japanese Pokémon YouTube channel):
This one was actually pretty funny. I came across it on Yahoo Japan for around 3000 Japanese Yen (~30 USD). Since the card itself without signature was going for around that price at the time, I just bought it on impulse, even though I had no idea who this Ponyta Ishii that was mentioned in the auction was. 
Soon after I heard he was just a pretty famous YouTuber, and thought: ah well, at least it was cheap… Only a year later I heard he was not just a random Japanese Pokémon YouTuber, but he was one of the two hosts for the official Japanese Pokémon TCG YouTube channel (together with Pippi Higuchi). Still not that special compared to an illustrator, but I’m still glad I bought it regardless.
All seven languages (+ additional English shatterfoil) for the XY Evolutions Pikachu, all eight signed by Mitsuhiro Arita:
When Mitsuhiro Arita visited Italy some people here on the forum were offering the option to send in cards to get signed by him. So, I took this opportunity to have this (most likely) one of a kind and unique set of all seven XY Evolution Pikachus signed by him, as well as an additional English Shatterfoil Pikachu from the Theme Deck I had lying around, because why not. 
And with only 5 euros a card it was also very cheap (it was that cheap that the price was raised to 10 or 15 euros per card two days later because too many people were sending in cards 
).
English XY BREAKthrough Pikachu signed by Ikue Ōtani (Japanese voice actress of Pikachu):
Came across this signed Pikachu on eBay for a pretty reasonable price. I’m still kinda doubting its legitimacy, though. I asked about opinions here on the forum in this thread. Comparing it to earlier signatures from her there are just a bit too many minor differences. I know signatures are never the same, and could slightly change over the years as well, but still…
If anyone else has any opinions about this signature, feel free to post it in that linked thread. One thing I do know is that the date is correct, since I’ve seen two other (English XY Evolution) Pikachu cards signed by Ikue Ōtani with that same date.
Jumbo Base Set Pikachu signed by Mitsuhiro Arita; Yukinori Torii; Richard Walkoski; Mike Boozer; Mike Gills; Steven Kam):
This is probably my favorite signed card. It contains the signatures of six different people. When I came across it on eBay I recognized Mitsuhiro Arita’s English and Japanese signatures, and decided to buy it. With loads of help here on the forum, we were able to determine who’s signatures these were.
Here all of them explained in a spoiler tag to keep this post somewhat compact per signed card:
I don’t think he needs introduction, but just in case relatively new collectors read this: Mitsuhiro Arita is a famous Japanese Pokémon illustrator. He’s been an active illustrator for the Pokémon TCG since the beginning. The Base Pikachu is one of his illustrations, but the recent Mewtwo GX 78/73 Secret Rare from SM Shining Legends (Mewtwo in the laboratory tube) is also his illustration for example. He signs either with his English or Japanese signature, or in this case above both. (Mitsuhiro Arita autographed cards are probably one of the easiest to find, since he signs a lot of them at Pokémon events, although they are still very popular.)
The PCL stands for Pokémon Card Laboratory. PCL employees are basically the creators of the Pokémon TCG in Japan, and they handle the R&D (Research & Development) of the Pokémon TCG. They are also in charge of designing new cards, and have authority on any matter related to the Pokémon TCG.
Source:
Yukinori Torii was showing some e-reader’s he created at one of the events. He worked in many Pokémon related games, and searching for his name on Bulbapedia results in multiple search results.
BDS is Richard Walkoski, a top level Pokémon TCG tournament organizer and judge, better known as Big Daddy Snorlax.
Source:
DMTM is Mike Boozer, better known as Dark Master Trainer Mike. He was a WotC representative and was present at Pokémon events in the early WotC days. He’s also pretty well-known for spreading the rumors and pictures of the Prerelease Raichu.
Source:
MTM is the signature of Mike Gills (the manager of organized play).
The last signature is from (Dark Master) Steven Kam. He was the manager of the marketing dept for WOTC and attended lots of Pokemon events back in the day.
Source for the last two signature of Mike Gillis and Steven Kam can be found here on the E4 forum thanks to @jkanly .
211/SM-P Promo Pikachu signed by illustrator Kouki Saitou:
Kouki Saitou was in the US a few months back. Someone here on the forum was arranging the possibility to let cards get signed again. Unfortunately I forgot after I read about that… But, when I came across this Pikachu soon after the event was over on eBay I couldn’t resist, especially because of the cute doodle that’s added. 
Jumbo Base Set Pikachu signed by Veronica Taylor with certificate of authentication:
When I came across this one on eBay I liked the added Certificate of Authenticity by the comic company Dynamic Forces, so decided to buy it for my collection. Simple as that.
English Holo FireRed LeafGreen Pikachu & Japanese PtS POP9 Pikachu both signed by illustrator Midori Harada:
These arrived today (April 11th, 2019), which is why I hadn’t created this thread a few days ago when @tonysandlin gave me the idea when he asked which autographed cards I had. These are signed at an event in Belgium, which my online friend and fellow Pikachu collector Tom arranged for me.
English POP4 Pikachu signed by illustrator Kouki Saitou:
This artwork is among my favorite Pikachu artworks, so when I had to opportunity to buy this card with the signature of its illustrator, I couldn’t let it pass.
Japanese Pikachu Gold Star and English Great Encounters Seviper signed by illustrator Masakazu Fukuda:
The latest signed cards for my collection, with a nice doodle and personalized “To Kevin C”. And this is also my very first signed Seviper card for my Seviper collection. A great addition, especially on such a nice artwork.
Japanese Holo Fossil Gengar signed by Dr. Sameji:
Sorry for the glare. Might make a new picture later on…
The only other non-Pikachu signed card I have. Bought it on impulse from Yahoo Japan because I liked the shark signature. This one is signed by Dr. Sameji, who is the voice actor in some of the Pokémon Game Boy games, and who attended events and tournaments pretty often. He also hosted a Japanese Pokémon radio show from 1997 to 2001 called Inuyama Inuko’s Pokémon Hour. His signature and picture can also be found at the back of the Tropical Present fan club promo post cards, as well as in some booklets and advert cards that came with Japanese promos.
So, those are all the autographed Pokémon cards currently in my possession. Feel free to share yours. Oh, and it doesn’t necessary have to be cards. If you have a binder or artwork signed by someone related to Pokémon, or even has some signed caps or socks for all I care, feel free to post it as well.
Greetz,
Quuador
