Former MK Dons midfielder Keith Andrews is to take up a full-time coaching role with the club this season.
Midfielder Gary Deegan has signed a new one-year deal at Southend.
Steve Clarke has expressed "deep regret" at his sacking by West Brom, claiming he had "unfinished business" at the Hawthorns.
Baggies head coach Clarke was dismissed on Saturday following a 1-0 Barclays Premier League defeat at Cardiff, the midlands outfit's fourth straight loss, with Roberto Di Matteo and Martin Jol the early favourites to succeed him.
Scotsman Clarke had just one full season in charge after a coaching career spent working under the likes of Jose Mourinho and Sir Bobby Robson and felt he deserved more time.
In a statement released by the League Managers Association, Clarke said: "I believe I have unfinished business at West Bromwich Albion Football Club so it is with deep regret that I was relieved of duties as Head Coach last night.
"I could not have been better prepared for my first job in management after over 14 years coaching experience learning from some of the great managers in the modern era. It was certainly a challenge to succeed Roy Hodgson, having been appointed England manager, after he successfully guided the club to a 10th place finish in 2011/12, after only securing their Barclays Premier League status the year before.
"It goes without saying that I was extremely proud to have built on that achievement by securing the club's highest ever finish in the Barclays Premier League and for over 30 years in the top flight by finishing eighth in 2012/13.
"Going into this season expectations were high, perhaps unrealistically so, but with it still being only our fourth consecutive season in the top flight, our primary objective had to be to establishing our status in the Barclays Premier League. I was, and remain convinced that we were well placed to achieve this aim.
"It has been an honour to manage this club and I would like to thank the staff who have assisted me in every possible way as well as the fans who have been tremendous throughout. Now, I wish everyone connected with the club the very best for the future."
The prospect of Di Matteo or Jol taking over has not gone down well with West Brom supporters' club secretary Alan Cleverley.
Di Matteo guided West Brom into the top flight in 2010 but was relieved of his duties in February 2011, while ex-Albion player Jol was recently dismissed as manager of Fulham.
Cleverley said: "If it's Jol, it is someone else's cast-off, while Di Matteo has done it before and wasn't a great success in the Premier League with us.
''I haven't seen a name yet where I think to myself 'yes, that would be fine'.''
After losing his job at West Brom, Di Matteo had a spell in charge at Chelsea that lasted from March to November 2012, during which the Blues won the Champions League and the FA Cup.
When it was put to him that Di Matteo had enjoyed considerable success since his stint with Albion, Cleverley said: ''He has, but I wonder why nobody else has gone for him since then?
''He might be favourite, but that one would surprise me more than anything.''
Also being tipped as contenders are the likes of Molde boss Ole Gunnar Solskjaer, former Schalke manager Ralf Rangnick and Aberdeen boss Derek McInnes, another ex-West Brom player.
Asked about Solskjaer - who, like Clarke was at West Brom, is in his first senior managerial job - Cleverley said: ''I wouldn't want an inexperienced manager coming in.
''Derek McInnes could be interesting. But I'd really like someone who has managed at a high level, even if he comes in from abroad.
''If you are trying someone out at this level, you might as well stay with Steve Clarke because if they are new to it, they could make a few mistakes and before you know it, you are bottom of the league.
''If you get someone who has managed in the top leagues abroad, they are going to be used to the pressure.''
Clarke departed with West Brom 16th in the table, two points above the relegation zone and having won only seven of their 34 top-flight matches in 2013.
The 50-year-old Scot - under whom Albion achieved their highest-ever Premier League finish of eighth last term - was appointed as their boss in the summer of 2012.
His deal with the club was due to run out at the end of this season and only late last month West Brom announced they planned to hold contract talks with him in the new year.
Cleverley said: ''Personally, I would have given him a little bit longer, but coming back from Cardiff on Saturday I would have said the coach was split about 50-50 on that.
''Some were for sacking him straight away. It really is a mixed one.
''I would have certainly seen it through to the end of the calendar year.
''It is not like we're adrift at the bottom, and the guy took us to eighth last year, which is overachieving.''